JavaScript确定数组是否包含值

var contains = function(needle) {    // Per spec, the way to identify NaN is that it is not equal to itself    var findNaN = needle !== needle;    var indexOf;    if(!findNaN && typeof Array.prototype.indexOf === 'function') {        indexOf = Array.prototype.indexOf;    } else {        indexOf = function(needle) { var i = -1, index = -1; for(i = 0; i < this.length; i++) {     var item = this[i];     if((findNaN && item !== item) || item === needle) {         index = i;         break;     } } return index;        };    }    return indexOf.call(this, needle) > -1;};

你可以像这样使用它：

var myArray = [0,1,2],    needle = 1,    index = contains.call(myArray, needle); // true