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  • js里json和eval()

    JSON
    * - JS中的对象只有JS自己认识,其他的语言都不认识
    * - JSON就是一个特殊格式的字符串,这个字符串可以被任意的语言所识别,
    * 并且可以转换为任意语言中的对象,JSON在开发中主要用来数据的交互
    * - JSON
    * - JavaScript Object Notation JS对象表示法
    * - JSON和JS对象的格式一样,只不过JSON字符串中的属性名必须加双引号
    * 其他的和JS语法一致
    * JSON分类:
    * 1.对象 {}
    * 2.数组 []
    *
    * JSON中允许的值:
    * 1.字符串
    * 2.数值
    * 3.布尔值
    * 4.null
    * 5.对象
    * 6.数组

    var arr = '[1,2,3,"hello",true]';
                
    var obj2 = '{"arr":[1,2,3]}';
                
    var arr2 ='[{"name":"孙悟空","age":18,"gender":"男"},{"name":"孙悟空","age":18,"gender":"男"}]';
    var json = '{"name":"孙悟空","age":18,"gender":"男"}';

    * JS对象 ---> JSON
    * JSON.stringify()
    * - 可以将一个JS对象转换为JSON字符串
    * - 需要一个js对象作为参数,会返回一个JSON字符串

    var o = JSON.parse(json);
    var o2 = JSON.parse(arr);
    var json = '{"name":"孙悟空","age":18,"gender":"男"}';
    var str = JSON.stringify(obj3);
    var str3 = '{"name":"孙悟空","age":18,"gender":"男"}';
    JSON.parse(str3);
                

    JSON这个对象在IE7及以下的浏览器中不支持,所以在这些浏览器中调用时会报错

    eval()
    * - 这个函数可以用来执行一段字符串形式的JS代码,并将执行结果返回
    * - 如果使用eval()执行的字符串中含有{},它会将{}当成是代码块
    * 如果不希望将其当成代码块解析,则需要在字符串前后各加一个()
    *
    * - eval()这个函数的功能很强大,可以直接执行一个字符串中的js代码,
    * 但是在开发中尽量不要使用,首先它的执行性能比较差,然后它还具有安全隐患
    */

    var str2 = "alert('hello');";
                
    var obj = eval("("+str+")");

    可以引入json.js达到兼容

    //  json2.js
    //  2016-05-01
    //  Public Domain.
    //  NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
    //  See http://www.JSON.org/js.html
    //  This code should be minified before deployment.
    //  See http://javascript.crockford.com/jsmin.html
    
    //  USE YOUR OWN COPY. IT IS EXTREMELY UNWISE TO LOAD CODE FROM SERVERS YOU DO
    //  NOT CONTROL.
    
    //  This file creates a global JSON object containing two methods: stringify
    //  and parse. This file is provides the ES5 JSON capability to ES3 systems.
    //  If a project might run on IE8 or earlier, then this file should be included.
    //  This file does nothing on ES5 systems.
    
    //      JSON.stringify(value, replacer, space)
    //          value       any JavaScript value, usually an object or array.
    //          replacer    an optional parameter that determines how object
    //                      values are stringified for objects. It can be a
    //                      function or an array of strings.
    //          space       an optional parameter that specifies the indentation
    //                      of nested structures. If it is omitted, the text will
    //                      be packed without extra whitespace. If it is a number,
    //                      it will specify the number of spaces to indent at each
    //                      level. If it is a string (such as "	" or " "),
    //                      it contains the characters used to indent at each level.
    //          This method produces a JSON text from a JavaScript value.
    //          When an object value is found, if the object contains a toJSON
    //          method, its toJSON method will be called and the result will be
    //          stringified. A toJSON method does not serialize: it returns the
    //          value represented by the name/value pair that should be serialized,
    //          or undefined if nothing should be serialized. The toJSON method
    //          will be passed the key associated with the value, and this will be
    //          bound to the value.
    
    //          For example, this would serialize Dates as ISO strings.
    
    //              Date.prototype.toJSON = function (key) {
    //                  function f(n) {
    //                      // Format integers to have at least two digits.
    //                      return (n < 10)
    //                          ? "0" + n
    //                          : n;
    //                  }
    //                  return this.getUTCFullYear()   + "-" +
    //                       f(this.getUTCMonth() + 1) + "-" +
    //                       f(this.getUTCDate())      + "T" +
    //                       f(this.getUTCHours())     + ":" +
    //                       f(this.getUTCMinutes())   + ":" +
    //                       f(this.getUTCSeconds())   + "Z";
    //              };
    
    //          You can provide an optional replacer method. It will be passed the
    //          key and value of each member, with this bound to the containing
    //          object. The value that is returned from your method will be
    //          serialized. If your method returns undefined, then the member will
    //          be excluded from the serialization.
    
    //          If the replacer parameter is an array of strings, then it will be
    //          used to select the members to be serialized. It filters the results
    //          such that only members with keys listed in the replacer array are
    //          stringified.
    
    //          Values that do not have JSON representations, such as undefined or
    //          functions, will not be serialized. Such values in objects will be
    //          dropped; in arrays they will be replaced with null. You can use
    //          a replacer function to replace those with JSON values.
    
    //          JSON.stringify(undefined) returns undefined.
    
    //          The optional space parameter produces a stringification of the
    //          value that is filled with line breaks and indentation to make it
    //          easier to read.
    
    //          If the space parameter is a non-empty string, then that string will
    //          be used for indentation. If the space parameter is a number, then
    //          the indentation will be that many spaces.
    
    //          Example:
    
    //          text = JSON.stringify(["e", {pluribus: "unum"}]);
    //          // text is '["e",{"pluribus":"unum"}]'
    
    //          text = JSON.stringify(["e", {pluribus: "unum"}], null, "	");
    //          // text is '[
    	"e",
    	{
    		"pluribus": "unum"
    	}
    ]'
    
    //          text = JSON.stringify([new Date()], function (key, value) {
    //              return this[key] instanceof Date
    //                  ? "Date(" + this[key] + ")"
    //                  : value;
    //          });
    //          // text is '["Date(---current time---)"]'
    
    //      JSON.parse(text, reviver)
    //          This method parses a JSON text to produce an object or array.
    //          It can throw a SyntaxError exception.
    
    //          The optional reviver parameter is a function that can filter and
    //          transform the results. It receives each of the keys and values,
    //          and its return value is used instead of the original value.
    //          If it returns what it received, then the structure is not modified.
    //          If it returns undefined then the member is deleted.
    
    //          Example:
    
    //          // Parse the text. Values that look like ISO date strings will
    //          // be converted to Date objects.
    
    //          myData = JSON.parse(text, function (key, value) {
    //              var a;
    //              if (typeof value === "string") {
    //                  a =
    //   /^(d{4})-(d{2})-(d{2})T(d{2}):(d{2}):(d{2}(?:.d*)?)Z$/.exec(value);
    //                  if (a) {
    //                      return new Date(Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4],
    //                          +a[5], +a[6]));
    //                  }
    //              }
    //              return value;
    //          });
    
    //          myData = JSON.parse('["Date(09/09/2001)"]', function (key, value) {
    //              var d;
    //              if (typeof value === "string" &&
    //                      value.slice(0, 5) === "Date(" &&
    //                      value.slice(-1) === ")") {
    //                  d = new Date(value.slice(5, -1));
    //                  if (d) {
    //                      return d;
    //                  }
    //              }
    //              return value;
    //          });
    
    //  This is a reference implementation. You are free to copy, modify, or
    //  redistribute.
    
    /*jslint
        eval, for, this
    */
    
    /*property
        JSON, apply, call, charCodeAt, getUTCDate, getUTCFullYear, getUTCHours,
        getUTCMinutes, getUTCMonth, getUTCSeconds, hasOwnProperty, join,
        lastIndex, length, parse, prototype, push, replace, slice, stringify,
        test, toJSON, toString, valueOf
    */
    
    
    // Create a JSON object only if one does not already exist. We create the
    // methods in a closure to avoid creating global variables.
    
    if (typeof JSON !== "object") {
        JSON = {};
    }
    
    (function () {
        "use strict";
    
        var rx_one = /^[],:{}s]*$/;
        var rx_two = /\(?:["\/bfnrt]|u[0-9a-fA-F]{4})/g;
        var rx_three = /"[^"\
    
    ]*"|true|false|null|-?d+(?:.d*)?(?:[eE][+-]?d+)?/g;
        var rx_four = /(?:^|:|,)(?:s*[)+/g;
        var rx_escapable = /[\"u0000-u001fu007f-u009fu00adu0600-u0604u070fu17b4u17b5u200c-u200fu2028-u202fu2060-u206fufeffufff0-uffff]/g;
        var rx_dangerous = /[u0000u00adu0600-u0604u070fu17b4u17b5u200c-u200fu2028-u202fu2060-u206fufeffufff0-uffff]/g;
    
        function f(n) {
            // Format integers to have at least two digits.
            return n < 10
                ? "0" + n
                : n;
        }
    
        function this_value() {
            return this.valueOf();
        }
    
        if (typeof Date.prototype.toJSON !== "function") {
    
            Date.prototype.toJSON = function () {
    
                return isFinite(this.valueOf())
                    ? this.getUTCFullYear() + "-" +
                            f(this.getUTCMonth() + 1) + "-" +
                            f(this.getUTCDate()) + "T" +
                            f(this.getUTCHours()) + ":" +
                            f(this.getUTCMinutes()) + ":" +
                            f(this.getUTCSeconds()) + "Z"
                    : null;
            };
    
            Boolean.prototype.toJSON = this_value;
            Number.prototype.toJSON = this_value;
            String.prototype.toJSON = this_value;
        }
    
        var gap;
        var indent;
        var meta;
        var rep;
    
    
        function quote(string) {
    
    // If the string contains no control characters, no quote characters, and no
    // backslash characters, then we can safely slap some quotes around it.
    // Otherwise we must also replace the offending characters with safe escape
    // sequences.
    
            rx_escapable.lastIndex = 0;
            return rx_escapable.test(string)
                ? """ + string.replace(rx_escapable, function (a) {
                    var c = meta[a];
                    return typeof c === "string"
                        ? c
                        : "\u" + ("0000" + a.charCodeAt(0).toString(16)).slice(-4);
                }) + """
                : """ + string + """;
        }
    
    
        function str(key, holder) {
    
    // Produce a string from holder[key].
    
            var i;          // The loop counter.
            var k;          // The member key.
            var v;          // The member value.
            var length;
            var mind = gap;
            var partial;
            var value = holder[key];
    
    // If the value has a toJSON method, call it to obtain a replacement value.
    
            if (value && typeof value === "object" &&
                    typeof value.toJSON === "function") {
                value = value.toJSON(key);
            }
    
    // If we were called with a replacer function, then call the replacer to
    // obtain a replacement value.
    
            if (typeof rep === "function") {
                value = rep.call(holder, key, value);
            }
    
    // What happens next depends on the value's type.
    
            switch (typeof value) {
            case "string":
                return quote(value);
    
            case "number":
    
    // JSON numbers must be finite. Encode non-finite numbers as null.
    
                return isFinite(value)
                    ? String(value)
                    : "null";
    
            case "boolean":
            case "null":
    
    // If the value is a boolean or null, convert it to a string. Note:
    // typeof null does not produce "null". The case is included here in
    // the remote chance that this gets fixed someday.
    
                return String(value);
    
    // If the type is "object", we might be dealing with an object or an array or
    // null.
    
            case "object":
    
    // Due to a specification blunder in ECMAScript, typeof null is "object",
    // so watch out for that case.
    
                if (!value) {
                    return "null";
                }
    
    // Make an array to hold the partial results of stringifying this object value.
    
                gap += indent;
                partial = [];
    
    // Is the value an array?
    
                if (Object.prototype.toString.apply(value) === "[object Array]") {
    
    // The value is an array. Stringify every element. Use null as a placeholder
    // for non-JSON values.
    
                    length = value.length;
                    for (i = 0; i < length; i += 1) {
                        partial[i] = str(i, value) || "null";
                    }
    
    // Join all of the elements together, separated with commas, and wrap them in
    // brackets.
    
                    v = partial.length === 0
                        ? "[]"
                        : gap
                            ? "[
    " + gap + partial.join(",
    " + gap) + "
    " + mind + "]"
                            : "[" + partial.join(",") + "]";
                    gap = mind;
                    return v;
                }
    
    // If the replacer is an array, use it to select the members to be stringified.
    
                if (rep && typeof rep === "object") {
                    length = rep.length;
                    for (i = 0; i < length; i += 1) {
                        if (typeof rep[i] === "string") {
                            k = rep[i];
                            v = str(k, value);
                            if (v) {
                                partial.push(quote(k) + (
                                    gap
                                        ? ": "
                                        : ":"
                                ) + v);
                            }
                        }
                    }
                } else {
    
    // Otherwise, iterate through all of the keys in the object.
    
                    for (k in value) {
                        if (Object.prototype.hasOwnProperty.call(value, k)) {
                            v = str(k, value);
                            if (v) {
                                partial.push(quote(k) + (
                                    gap
                                        ? ": "
                                        : ":"
                                ) + v);
                            }
                        }
                    }
                }
    
    // Join all of the member texts together, separated with commas,
    // and wrap them in braces.
    
                v = partial.length === 0
                    ? "{}"
                    : gap
                        ? "{
    " + gap + partial.join(",
    " + gap) + "
    " + mind + "}"
                        : "{" + partial.join(",") + "}";
                gap = mind;
                return v;
            }
        }
    
    // If the JSON object does not yet have a stringify method, give it one.
    
        if (typeof JSON.stringify !== "function") {
            meta = {    // table of character substitutions
                "": "\b",
                "	": "\t",
                "
    ": "\n",
                "f": "\f",
                "
    ": "\r",
                """: "\"",
                "\": "\\"
            };
            JSON.stringify = function (value, replacer, space) {
    
    // The stringify method takes a value and an optional replacer, and an optional
    // space parameter, and returns a JSON text. The replacer can be a function
    // that can replace values, or an array of strings that will select the keys.
    // A default replacer method can be provided. Use of the space parameter can
    // produce text that is more easily readable.
    
                var i;
                gap = "";
                indent = "";
    
    // If the space parameter is a number, make an indent string containing that
    // many spaces.
    
                if (typeof space === "number") {
                    for (i = 0; i < space; i += 1) {
                        indent += " ";
                    }
    
    // If the space parameter is a string, it will be used as the indent string.
    
                } else if (typeof space === "string") {
                    indent = space;
                }
    
    // If there is a replacer, it must be a function or an array.
    // Otherwise, throw an error.
    
                rep = replacer;
                if (replacer && typeof replacer !== "function" &&
                        (typeof replacer !== "object" ||
                        typeof replacer.length !== "number")) {
                    throw new Error("JSON.stringify");
                }
    
    // Make a fake root object containing our value under the key of "".
    // Return the result of stringifying the value.
    
                return str("", {"": value});
            };
        }
    
    
    // If the JSON object does not yet have a parse method, give it one.
    
        if (typeof JSON.parse !== "function") {
            JSON.parse = function (text, reviver) {
    
    // The parse method takes a text and an optional reviver function, and returns
    // a JavaScript value if the text is a valid JSON text.
    
                var j;
    
                function walk(holder, key) {
    
    // The walk method is used to recursively walk the resulting structure so
    // that modifications can be made.
    
                    var k;
                    var v;
                    var value = holder[key];
                    if (value && typeof value === "object") {
                        for (k in value) {
                            if (Object.prototype.hasOwnProperty.call(value, k)) {
                                v = walk(value, k);
                                if (v !== undefined) {
                                    value[k] = v;
                                } else {
                                    delete value[k];
                                }
                            }
                        }
                    }
                    return reviver.call(holder, key, value);
                }
    
    
    // Parsing happens in four stages. In the first stage, we replace certain
    // Unicode characters with escape sequences. JavaScript handles many characters
    // incorrectly, either silently deleting them, or treating them as line endings.
    
                text = String(text);
                rx_dangerous.lastIndex = 0;
                if (rx_dangerous.test(text)) {
                    text = text.replace(rx_dangerous, function (a) {
                        return "\u" +
                                ("0000" + a.charCodeAt(0).toString(16)).slice(-4);
                    });
                }
    
    // In the second stage, we run the text against regular expressions that look
    // for non-JSON patterns. We are especially concerned with "()" and "new"
    // because they can cause invocation, and "=" because it can cause mutation.
    // But just to be safe, we want to reject all unexpected forms.
    
    // We split the second stage into 4 regexp operations in order to work around
    // crippling inefficiencies in IE's and Safari's regexp engines. First we
    // replace the JSON backslash pairs with "@" (a non-JSON character). Second, we
    // replace all simple value tokens with "]" characters. Third, we delete all
    // open brackets that follow a colon or comma or that begin the text. Finally,
    // we look to see that the remaining characters are only whitespace or "]" or
    // "," or ":" or "{" or "}". If that is so, then the text is safe for eval.
    
                if (
                    rx_one.test(
                        text
                            .replace(rx_two, "@")
                            .replace(rx_three, "]")
                            .replace(rx_four, "")
                    )
                ) {
    
    // In the third stage we use the eval function to compile the text into a
    // JavaScript structure. The "{" operator is subject to a syntactic ambiguity
    // in JavaScript: it can begin a block or an object literal. We wrap the text
    // in parens to eliminate the ambiguity.
    
                    j = eval("(" + text + ")");
    
    // In the optional fourth stage, we recursively walk the new structure, passing
    // each name/value pair to a reviver function for possible transformation.
    
                    return (typeof reviver === "function")
                        ? walk({"": j}, "")
                        : j;
                }
    
    // If the text is not JSON parseable, then a SyntaxError is thrown.
    
                throw new SyntaxError("JSON.parse");
            };
        }
    }());
    json.js
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  • 原文地址:https://www.cnblogs.com/hack-ing/p/11916967.html
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