function lambda(l) { var fn = l.match(/\((.*)\)\s*=>\s*(.*)/); var p = []; var b = ""; console.log(fn) if (fn.length > 0) { fn.shift(); } if (fn.length > 0) { b = fn.pop();} if (fn.length > 0) { p = fn.pop() .replace(/^\s*|\s(?=\s)|\s*$|,/g, '').split(' '); console.log("p = ", p); } console.log(fn) fn = ((! /\s*return\s+/.test(b)) ? "return " : "") + b; console.log(fn) p.push(fn); console.log("p2 = ", p); try { return Function.apply({}, p); } catch (e) { return null; } } Array.prototype.where = function (f) { var fn = f; if (typeof f == "string") { console.log('001'); if ((fn = lambda(fn)) === null) { console.log("Syntax error in lambda string: " + f); return; console.log('null') } var res = []; var l = this.length; var p = [0, 0, res]; for (var i = 1; i < arguments.length; i++) { p.push(arguments[i]); console.log('3')} console.log(p) for (var i = 0; i < l; i++) { if (typeof this[i] == "undefined") { continue; console.log('4')} p[0] = this[i]; console.log(p) p[1] = i; console.log(p) if (!!fn.apply(this, p)) { res.push(this[i]);} } console.log('成功！') return res; } } var a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; console.log(Array.prototype.where); console.log(Array.prototype.slice); a.where('( ) => true');

大大，没有用~您可以去试试，真的undefined···不知道官方会怎么说