eval() / Function()

var o1 = new function(){
        return "晶晶";
    };
    console.log("o1",JSON.stringify(o1));


    var o2 = new function(){
        this.name = "nick";
    };
    console.log("o2",JSON.stringify(o2));


    var o3 = new function(){
        this.name = "xian";
        return "gege";
    };
    console.log("o3",JSON.stringify(o3));

一. function(){}  / new function(){}的区别。

二. eval / new Function /(function(){})()

console.log(typeof un);
    console.log(typeof deux);
    console.log(typeof trois);

    var jsstring = "var un = 1; console.log(un);";
    eval(jsstring);//1

    jsstring = "var deux = 2;console.log(deux);";
    new Function(jsstring)();// 2

    jsstring = "var trois = 3; console.log(trois);";
    (function(){
        eval(jsstring); // 3
    })()    

    console.log(typeof un); // number
    console.log(typeof deux); // undefined
    console.log(typeof trois);// undefined

eval("var arr = [12,3,4];console.log(arr);");// eval() 跟 new Function() 传入字符串

console.log(arr); // [12,3,4];   eval()可以访问和修改它外部的变量，这是Function做不来的！

(function(){
        var local = 1;
        eval("local = 2; console.log(local)");// 2
        console.log(local);// 2
    })();

    

    (function(){
        var local = 1;
        Function("console.log(typeof local);")();// undefined
    })();


    (function(){
        var local = 1;
        eval("console.log(local)");// 1
        console.log(local);// 1
    })();

    (function(){
        var local = 1;
        Function("console.log(" + local + ");")();// 1
    })();

  

eval() 与 JSON数据格式- 需要加上() 将代码块转为表达式