.forEach循环：使用变量 [英] .forEach loop: use variable

问题描述

我循环遍历一组16个ID并为每个ID分配一个 eventListener 。我想向我的php文件发送一个数字（第一个id为1，第二个为2，等等），但似乎 i 比我更有活力我希望它是。每个id发送 17 。

I'm looping through a set of 16 ids and assigning an eventListener to each one. I want to send a number to my php file (1 for the first id, 2 for the second, etc, etc), but it seems that i is more dynamic than I'd like it to be. Every id sends 17.

klasses.forEach(function(klass){
    var svgElement = svgDoc.getElementById(klass); //get the inner element by id
    svgElement.addEventListener("mouseup",function(){
        $.ajax({
            type: "POST",
            url: "buildService.php",
            data: { "service" : i}
        }).done(function(msg){
            alert(lameArray[i]);
            $("#modalSpan").html(msg);
            $("#modmodal").modal();
        });
    });
    i++;
});

如何将每一个设置为特定数字？我也尝试过：

How can I set each one to a specific number? I've also tried:

var lameArray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];
...
data: { "service" : lameArray[i]}

推荐答案

什么是我？问题是 i 是一个全局变量，或者是 forEach 循环之外的变量，所以当 mouseup 事件被触发， istant中 i 的值被使用，而不是一个它定义了事件监听器。

What's i? The problem is that i is a global variable, or a variable outside the forEach cycle anyway, so when the mouseup event is triggered, the value of i in that istant is used, and not the one it had when the event listener is defined.

请注意，因为你使用 forEach ，回调函数实际上是用第二个参数调用的，它是计数器。所以你可以使用：

Mind you, since you're using forEach, that the callback function actually is called with a second parameter, which is the counter. So you can use:

klasses.forEach(function(klass, i) {
    ...
});

现在， i 是一个变量 forEach 范围，并满足您的目的。 （ forEach 也使用第三个参数调用回调函数，即你自己的集合本身 - klasses 。）

Now, i is a variable in the forEach scope, and serves your purposes. (forEach calls the callback function with a third parameter too, that is the collection itself - klasses in your case.)

注意：由于您使用的是jQuery，因此您应该使用更类似jQuery的样式进行编码。所以改变你的代码是这样的：

Note: since you're using jQuery, you should code with a more "jQuery-like" style. So change your code in something like this:

$.each(klasses, function(i, klass) {
    $("#" + klass).mouseup(function(){
        $.ajax({
            type: "POST",
            url: "buildService.php",
            data: {service: i + 1}
            ...
        });
    });
});

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