1、为Array原型添加indexOf方法(如果学过面向对象,相当于给Array类添加实例方法),方法体如下:
//添加数组IndexOf方法 if (!Array.prototype.indexOf){Array.prototype.indexOf = function(elt /*, from*/){var len = this.length >>> 0;var from = Number(arguments[1]) || 0;from = (from < 0)? Math.ceil(from): Math.floor(from);if (from < 0)from += len;for (; from < len; from++){if (from in this && this[from] === elt)return from;}return -1;}; }
2、使用jQuery的inArray方法,注:jQuery版本2.0以上不再支持IE8
var arr = [ 1, "2", false, "aaa" ]; jQuery.inArray("aaa", arr); jQuery.inArray(false, arr); jQuery.inArray("2", arr); jQuery.inArray(1, arr, 2);
不存在就为-1;