使用Object.assign对对象所做的更改会使源对象发生变化 [英] Changes to object made with Object.assign mutates source object

问题描述

我的react-redux应用程序中有以下reducer代码:

I have following reducer code in my react-redux app:

    case 'TOGGLE_CLIENT_SELECTION':
        const id = action.payload.id;
        let newState = Object.assign({}, state);
        newState.list.forEach((client) => {
            if (client.id == id) client.selected = !client.selected;
        });
        console.log(state.list[0].selected + ' - ' + newState.list[0].selected)
        return newState;

如果我做对了-Object.assign创建了一个全新的对象，但是console.log显示了"false-false"的"true-true".有什么想法为什么它会这样，我该如何避免这种行为?

If I got it right - Object.assign creates brand new object, but console.log displays "true - true" of "false - false". Any thoughts why it behaves like this and how can I avoid this behavior?

推荐答案

是正确的，但这不是深层副本.

True, but it's not a deep copy.

新对象包含对旧列表的引用.

The new object contains a reference to the old list.

这是解决它的一个窍门(有人可能会说更"正确的方式):

Here's a trick to get around it (there's more "proper" ways some might say):

JSON.stringify原始.然后JSON.parse该字符串.新对象将是深层复制"(不确定在技术上是否真的是深层复制").除非您的子类型比标准的普通旧JSON可接受的东西更复杂，否则它会很好地工作.

JSON.stringify the original. Then JSON.parse that string. The new object will be a "deep" copy (not sure if that's really technically "deep copying"). It works fine unless your sub-types are something more complex than standard plain old JSON-acceptable stuff.

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