判断一个变量是否在一个数组里

function IsInArray(arr,val){

    var testStr=','+arr.join(",")+",";

    return testStr.indexOf(","+val+",")!=-1;

}




var test=['a',23,-1];

alert(IsInArray(test,'a'));//true
alert(IsInArray(test,2));//false
alert(IsInArray(test,-1));//true