Question

我试图像对待数组一样遍历对象。我正在努力将循环计数器附加到变量名。

我有一个这样的对象（output with dump(), which I found here）：

object(2): {
  elem0:  array(4): {
    [0]:  string(27): "http://placehold.it/300x300"
    [1]:  string(3): "0.8"
    [2]:  string(4): "-150"
    [3]:  string(3): "200"
  }
  elem1:  array(4): {
    [0]:  string(27): "http://placehold.it/300x300"
    [1]:  string(3): "0.6"
    [2]:  string(3): "-70"
    [3]:  string(3): "458"
  }
}

以下是我试图循环播放的方法：

jQuery(document).ready(function($) {

    // Provides object-measuring functionality
    Object.size = function(obj) {
        var size = 0, key;
        for (key in obj) {
            if (obj.hasOwnProperty(key)) size++;
        }
        return size;
    };

    // Returns the number of objects in my object
    var size = Object.size(window.depthElems);

    /*
    This is where I'm having difficulty.
    I would like to use window.depthElems.elem0,
    then window.depthElems.elem1, etc.
    */

    for (var i = 0; i < size; i++) {
        $('.wrapper').append('<img src="' + window.depthElems.elem+i+[0] + '" />'); 
    }

});

Answer 1

为了论证，我也会提出我的问题作为答案。您可以使用：

for(element in window.depthElems) {
    if(window.depthElems.hasOwnProperty(element)) {
        $('.wrapper').append('<img src="' + window.depthElems[element] + '" />');
    }
}

这不仅更优雅，而且还需要更少的代码。当然，如果有理由使用其他代码，请说出来。

注意：编辑此代码还包括读取“数组”的功能，但问题是使其与“对象”一起使用。如果使用'对象'，'hasOwnProperty'检查是多余的。

注意＃2：您也可以使用 Azder 之类的var hasOwn = Object.prototype.hasOwnProperty;，这是一个很好的保护措施。

Answer 2

如果我的答案超过了顶部我很抱歉，我只是想通过错过使用JS来防止进一步的伤害（我经历了很多）。

jQuery(document).ready(function($) {

    var i; // there is no block scope in JS, so better to be clear and define i here
    var $wrapper; // also

    // Changing the JS built-in objects is problematic most of the time
    // You should learn from jQuery and do wrapping instead
    // Or at least just a good namespasing like:
    // MyFramework.objectSize = function (obj) {}

    Object.size = function(obj) {
        var size = 0, key;
        var hasOwn = Object.prototype.hasOwnProperty; // will explain further down
        for (key in obj) {
            // if obj has redifined hasOwnProperty = function(){ return false; }?
            // it's better to use hasOwn like this if(hasOwn.call(obj,key)) {}
            // and please do use braces even if only 1 statement
            if(hasOwn.call(obj,key)) size++;
        }
        return size;
    };

    // Returns the number of objects in my JSON object
    var size = Object.size(window.depthElems);

    $wrapper = $('.wrapper'); // cached so jQuery doesn't search for it each iteration    

    // i is scoped to the whole function anyways
    for (i = 0; i < size; i++) {

        // $.each even guards you of the changing DOM which can cause
        // infinite loops (you don't have that problem here, but... good to know
        $.each(window['depthElems'+i],function(index,element){
            $wrapper.append('<img src="' + element + '" />');
        }); 
    }

});

另外，既然你已经创建了名为elem1，elem2，elem3，...的对象，你也可以使用二维数组，如window.depthElems = [[],[],[]]

循环使用增量属性名称的对象

2 个答案: