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[英]When I assign an object to a property of an object, does the property become an object? If so, how do I access the first object via the second one?
[英]How do I access an object via another object that contains an object which is a property of the object I want to have access to?
很難想出這個標題,希望它是可以理解的並且有意義。
好吧,也許,拿出標題的難度反映了這種情況的一些不必要的復雜性-如果有一種簡單的方法,我很想知道。
在此示例中,有一個Car'class',可以從中實例對象(Cars)。 它有一個模板(實際上是一個SVG,實際上不是汽車,但在乎誰),還有一個公共方法,用於通過jQuery修改模板。
在carContainerClick()函數中,如何訪問其模板包含在當前單擊的carContainer元素中的Car實例?
$(function(){
var cars = [];
for (var i = 0; i < 2; i++) {
var carContainer = $('<div/>', { class: 'car-container'});
var car = new Car();
cars[i] = car;
carContainer.on('click', carContainerClick);
carContainer.append(car.getTemplate());
$('.container').append(carContainer);
}
function carContainerClick() {
// HERE - how do I access the Car instance whose template is contained by the currently clicked carContainer element?
cars[0].changeColor();
}
});
function Car () {
this.template = $('<svg viewBox="0 0 301 259"> <g class="svg-group"><path class="stick-2" fill-rule="evenodd" clip-rule="evenodd" d="M74.192,27.447c2.589-2.042,4.576-3.188,6.991-5.093c0,0,1.753-1.11,0.416-2.945 c-1.13-1.546-3.242,0.014-3.242,0.014c-4.831,3.804-9.678,7.589-14.491,11.418c-2.335,1.861-4.335,4.009-7.954,3.233 c-2.136-0.458-3.892,1.798-3.913,4.021c-0.02,2.326,1.531,4.107,3.734,4.296c2.353,0.2,4.689-1.183,4.635-3.241 c-0.066-2.415,1.215-3.474,2.981-4.492c1.821-1.049,5.809-3.993,7.21-4.785C71.961,29.082,74.192,27.447,74.192,27.447z"/></g></svg>');
}
Car.prototype = {
getTemplate: function() {
return this.template;
},
changeColor: function() {
console.log('changeColor');
$('.svg-group', this.template).find("path, polygon, circle").attr("fill", "#aff");
}
};
更新
您可以將內聯函數用作將car
作為參數傳遞的事件處理程序...但是,由於car
聲明是從循環中提升的(特別是在當前函數的頂部),因此需要確保事件處理程序捕獲正確的Car
實例,而不是最后一個要通過循環的實例。
您可以通過創建一個新的范圍自調用函數表達式創建一個封閉car
內環路存在,並且允許當您設置處理程序來捕捉正確的汽車實例。
for (var i = 0; i < 2; i++) {
(function(){
var carContainer = $('<div/>', { class: 'car-container'});
var car = new Car();
cars[i] = car;
carContainer.on('click', function(){
carContainerClick(car);
});
carContainer.append(car.getTemplate());
$('.container').append(carContainer);
})();
}
現在,您可以擁有一個傳遞所需的Car
實例的函數。
function carContainerClick(car) {
car.changeColor();
}
使用閉包將car實例作為參數傳遞給carContainerClick
函數。
我提取了一個新函數,因為在for循環中執行此操作可能無法正常工作(始終將最后一輛車作為參數傳遞)
for (var i = 0; i < 2; i++) {
var carContainer = $('<div/>', { class: 'car-container'});
var car = new Car();
cars[i] = car;
bindCarContainer(carContainer, car);
carContainer.append(car.getTemplate());
$('.container').append(carContainer);
}
function bindCarContainer(carContainer, car) {
carContainer.on('click', function(event) {
carContainerClick.call(this, car, event);
});
}
function carContainerClick(car, event) {
//...
}
嘗試分配將其存儲在屬性中:
$container = $('.container');
for (var i = 0; i < 2; ++i) {
var car = new Car(),
carContainer = $('<div/>').addClass('car-container').prop('car', car);
carContainer.on('click', carContainerClick);
carContainer.append(car.getTemplate());
$container.append(carContainer);
}
function carContainerClick() {
this.car.changeColor();
}
var $template = $('<svg viewBox="0 0 301 259"> <g class="svg-group"><path class="stick-2" fill-rule="evenodd" clip-rule="evenodd" d="M74.192,27.447c2.589-2.042,4.576-3.188,6.991-5.093c0,0,1.753-1.11,0.416-2.945 c-1.13-1.546-3.242,0.014-3.242,0.014c-4.831,3.804-9.678,7.589-14.491,11.418c-2.335,1.861-4.335,4.009-7.954,3.233 c-2.136-0.458-3.892,1.798-3.913,4.021c-0.02,2.326,1.531,4.107,3.734,4.296c2.353,0.2,4.689-1.183,4.635-3.241 c-0.066-2.415,1.215-3.474,2.981-4.492c1.821-1.049,5.809-3.993,7.21-4.785C71.961,29.082,74.192,27.447,74.192,27.447z"/></g></svg>');
function Car () {
this.$template = $template.clone();
}
Car.prototype = {
getTemplate: function() {
return this.$template;
},
changeColor: function() {
console.log('changeColor');
$('.svg-group', this.$template).find("path, polygon, circle").attr("fill", "#aff");
}
};
一些注意事項:
$
來使元素進入循環,這非常慢! 將結果存儲在循環之前的變量中 { class: 'car-container'}
在舊版瀏覽器上可能會失敗,因為class
是保留的。 嘗試使用帶引號或addClass
方法的'class'
。 $
。 使用jQuery的.data()
將對汽車的引用附加到模板:
function Car () {
this.template = $('<svg viewBox="0 0 301 259"> <g class="svg-group"><path class="stick-2" fill-rule="evenodd" clip-rule="evenodd" d="M74.192,27.447c2.589-2.042,4.576-3.188,6.991-5.093c0,0,1.753-1.11,0.416-2.945 c-1.13-1.546-3.242,0.014-3.242,0.014c-4.831,3.804-9.678,7.589-14.491,11.418c-2.335,1.861-4.335,4.009-7.954,3.233 c-2.136-0.458-3.892,1.798-3.913,4.021c-0.02,2.326,1.531,4.107,3.734,4.296c2.353,0.2,4.689-1.183,4.635-3.241 c-0.066-2.415,1.215-3.474,2.981-4.492c1.821-1.049,5.809-3.993,7.21-4.785C71.961,29.082,74.192,27.447,74.192,27.447z"/></g></svg>');
this.template.data('car', this);
}
然后,您可以從jQuery對象訪問它:
function carContainerClick() {
var car = this.data('car');
car.changeColor();
}
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