js常用数据转换&判断

• 数组转字符串

var a, b;
a = new Array(0,1,2,3,4);
b = a.join("-");      //"0-1-2-3-4"

• 字符串转数组

var s = "abc,abcd,aaa";
ss = s.split(",");// 在每个逗号(,)处进行分解  ["abc", "abcd", "aaa"]
var s1 = "helloworld";
ss1 = s1.split('');  //["h", "e", "l", "l", "o", "w", "o", "r", "l", "d"]

• 转成num Number(this.totalPage)
• 转为整型 parseInt(num)
• 转换成变量名 eval('items' + this.userType)

判断一个字符串是否存在于一个字符串数组中

1. 正则表达式

Array.prototype.in_array=function(e){
    var r=new RegExp(','+e+',');
    return (r.test(','+this.join(this.S)+','));
};
arr.in_array('b');

注：此函数只对字符和数字有效

2. 遍历

Array.prototype.in_array = function (element) {
    for (var i = 0; i < this.length; i++) {
        if (this[i] == element) {
            return true;
        }
    }
    return false;
}
arr.in_array('test');

3. indexOf()

function IsInArray(arr,val){
　　var testStr=','+arr.join(",")+",";
　　return testStr.indexOf(","+val+",")!=-1;
}
IsInArray(arr,'test');

注：IE9以下不支持Array的indexOf