如何為 setTimeout() 方法傳參

現有如下JavaScript代碼：

function printApple(apple){

　　console.log(apple, "is a kind of healthy fruit");

}

var apple = "apple";

setTimeout("printApple(apple)", 5000);

則在執行setTimeout時，會報 apple is not defined，那么應該如何傳參數呢？

1、 匿名函數

setTimeout(function(){

　　console.log(apple, "is a kind of healthy fruit");

}, 5000);

2、Function.prototype.bind()

setTimeout(printApple.bind(null, apple), 5000);

3、第三個參數作為 setTimeout() 內部函數的參數，其實setTimeout()可以接受多個參數：setTimeout(yourFunctionReference, 5000, param1, param2, paramN);

var apple = "apple";

setTimeout(printApple, 5000, apple);

由於IE10以前的版本，不支持為setTimeout()和setInterval()方法傳遞第三個參數，所以在IE10以前的版本使用時，要添加以下代碼：

if (document.all && !window.setTimeout.isPolyfill) { var __nativeST__ = window.setTimeout; window.setTimeout = function (vCallback, nDelay /*, argumentToPass1, argumentToPass2, etc. */) { var aArgs = Array.prototype.slice.call(arguments, 2); return __nativeST__(vCallback instanceof Function ? function () { vCallback.apply(null, aArgs); } : vCallback, nDelay); }; window.setTimeout.isPolyfill = true; } if (document.all && !window.setInterval.isPolyfill) { var __nativeSI__ = window.setInterval; window.setInterval = function (vCallback, nDelay /*, argumentToPass1, argumentToPass2, etc. */) { var aArgs = Array.prototype.slice.call(arguments, 2); return __nativeSI__(vCallback instanceof Function ? function () { vCallback.apply(null, aArgs); } : vCallback, nDelay); }; window.setInterval.isPolyfill = true; }

Any anonymous function will change "this" to point to window, so you will lose your object reference.