jQuery $ .extend而不覆盖目标属性 [英] jQuery $.extend without overriding target properties

问题描述

是否可以在不覆盖已设置属性的情况下扩展对象? 在下面的示例中，我正在寻找一种为猫添加2个翅膀的方法，但要保持它的4条腿.

Is it possible to extend an object without overriding the properties that are already set? In the following example I'm looking for a way to add 2 wings to the cat, but keepings it's 4 legs.

var cat  = { legs: 4 };
var bird = { legs: 2, wings: 2 }

// some references in my application to the original cat
var some_cat = cat;

$.extend( cat, bird );

// expected { legs: 4, wings: 2 }
console.log( some_cat );

更新

我忘记在原始问题/示例中弄清楚了，但重要的是，它修改了原始的cat对象.

I forgot to make it clear in the original question / example, but it is important that it modifies the original cat object.

推荐答案

尝试类似-

for (prop in bird) {
    if(!cat.hasOwnProperty(prop)) {
        cat[prop] = bird[prop];
    }
}

cat = {腿:4，翅膀:2}之后

After cat = {legs: 4, wings: 2}

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