【JS】引用类型之String

由于String的方法过多，这里只列举一下常用的但又不是很熟的

1、replace()

var text = "cat, bat, sat, fat"; 

var result = text.replace("at", "ond");
alert(result);    //"cond, bat, sat, fat"   替换第一个

result = text.replace(/at/g, "ond");
alert(result);    //"cond, bond, sond, fond"   //替换全部

result = text.replace(/(.at)/g, "word ($1)");
alert(result);    //word (cat), word (bat), word (sat), word (fat)    //使用特殊的字符序列替换，字符序列有（$$、$&、$`、$'、$n、$nn）,具体用法需要时查

function htmlEscape(text){
    return text.replace(/[<>"&]/g, function(match, pos, originalText){
        switch(match){
            case "<":
                return "&lt;";
            case ">":
                return "&gt;";
            case "&":
                return "&amp;";
            case "\"":
                return "&quot;";
        }             
    });
}

alert(htmlEscape("<p class=\"greeting\">Hello world!</p>")); //&lt;p class=&quot;greeting&quot;&gt;Hello world!&lt;/p&gt;

2、localeCompare()

基于时区(地区)的比较函数

var stringValue = "yellow";       
alert(stringValue.localeCompare("brick"));  //1
alert(stringValue.localeCompare("yellow")); //0
alert(stringValue.localeCompare("zoo"));    //-1

//preferred technique for using localeCompare()
function determineOrder(value) {
    var result = stringValue.localeCompare(value);
    if (result < 0){
        alert("The string 'yellow' comes before the string '" + value + "'.");
    } else if (result > 0) {
        alert("The string 'yellow' comes after the string '" + value + "'.");
    } else {
        alert("The string 'yellow' is equal to the string '" + value + "'.");
    }
}

determineOrder("brick");
determineOrder("yellow");
determineOrder("zoo");

3、slice()/substring()/substr()

var stringValue = "hello world";
alert(stringValue.slice(3));        //"lo world"
alert(stringValue.substring(3));    //"lo world"
alert(stringValue.substr(3));       //"lo world"
alert(stringValue.slice(3, 7));     //"lo w"
alert(stringValue.substring(3,7));  //"lo w"
alert(stringValue.substr(3, 7));    //"lo worl"

alert(stringValue.slice(-3));         //"rld"
alert(stringValue.substring(-3));     //"hello world"
alert(stringValue.substr(-3));        //"rld"
alert(stringValue.slice(3, -4));      //"lo w"
alert(stringValue.substring(3, -4));  //"hel"
alert(stringValue.substr(3, -4));     //"" (empty string)