問題描述

我正在嘗試創(chuàng)建一個循環(huán)來創(chuàng)建許多函數(shù)，以便當用戶單擊拇指向上按鈕時，它會運行正確的 .php 文檔.當我刪除循環(huán)并只給 var i 一個特定的數(shù)字時，它工作得很好，但是一旦我嘗試將它變成一個循環(huán)，在 alert(i) 我在第一個循環(huán)中得到 10.

I am trying to create a loop to create many functions so that when a user clicks the thumb up button it runs the correct .php document. It works great when I remove the loop and just give var i a specific number but as soon as i try to make it into a loop, at the alert(i) i get 10 on the first loop.

 var i=1;
 while ( ++i < 10 ) {
    $('#thumbup' + i).click(function() {
        var userid = $('#theuser' + i).text();
        var url = "_thumbup.php?userid=" + userid;
        //alert(url);

        $('#thumbup' + i).hide();
        $('#thumbdown' + i).hide();

        $("#toggle").css("display","block");
        alert(i); // Give me 10 on first loop?!?

        // get the URL
        http = new XMLHttpRequest(); 
        http.open("GET", url, true);
        http.send(null);

        // prevent form from submitting
        return false;   

    }); 
  }

推薦答案

這是一個經(jīng)典問題:當你的回調(diào)被調(diào)用時，i 的值是 end of loop.

This is a classical problem : by the time your callbacks are called, i has the value of end of loop.

解決方法如下:

var i=1;
while ( ++i < 10 ) {
   (function(i){
      // your current code
   })(i);
}

之所以有效，是因為內(nèi)部函數(shù)在調(diào)用時創(chuàng)建了一個作用域，而這個作用域包含了你想要的i的值.

It works because the internal function creates a scope when it is called, and this scope contains the value of i you want.

這篇關(guān)于Jquery 循環(huán)無法正常工作?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！