RegExp

var str = "1a1b1c";
var reg = new RegExp("1(.)", "g");
alert(reg.test(str)); // true
alert(reg.test(str)); // true
/*alert(reg.test(str)); // trued
alert(reg.test(str)); // trued */
alert(RegExp.$1);

/*
var reg = new RegExp("1.", "g");
alert(reg.exec(str)[0]);
alert(reg.exec(str)[0]); */

格式: http://www.cnblogs.com/shi0090/p/5971554.html
var expression=/at/gi;
expression = new RegExp(pattern, flags); \\[ 脱离转义符
正则转义符：( [ { \ ^ $ | ) ? * + . ] } 加入 \[ 脱离转义符

.可变身
[ab]只能变成a,b

转义作用()
var text = "mom and dad and baby";
var pattern = /mom( and dad( and baby)?)?/gi;

var matches = pattern.exec(text);
console.log(matches.index); // 0
console.log(matches.input); // "mom and dad and baby"
console.log(matches[0]); // "mom and dad and baby"
console.log(matches[1]); // " and dad and baby"
console.log(matches[2]); // " and baby"

var text = "000-00-0000";
var pattern = /\d{3}-\d{2}-\d{4}/;

if (pattern.test(text)){
console.log("The pattern was matched.");
}

var text = "this has been a xhort summer";
var pattern = /(.)hort/g;

if (pattern.test(text)){

console.log(RegExp.leftContext); // this has been a
console.log(RegExp.rightContext); // summer
console.log(RegExp.lastMatch); // short
console.log(RegExp.lastParen); // s
console.log(RegExp.$1);
console.log(RegExp.multiline); // false
}

var a = 'aaaa'.match(/\w/g);
console.log(a); // ["a", "a", "a", "a"]

var a = 'aaaa'.match(/\w/);
console.log(a); // ["a", index: 0, input: "aaaa"]

'aaaa'.replace('a', 'b') //"baaa"