在不破坏嵌套对象属性的情况下扩展对象？

Question

I have an object with some nested objects, I want to extend the object and in some cases the nested objects will be returned as empty although I'd like to preserve these - can anyone recommend how I can do this?

    let myObject = {
    id: 1,
    configs: {
        track: true,
        pulse: false
    },
    name: 'slider',
    position: 1
}

let updatedObject = Object.assign({}, myObject, {
    name: 'scroller',
    configs: {}
})

// outputs {id: 1, configs: {}, name: 'scroller', position: 1}

found this useful plugin https://www.npmjs.com/package/deepmerge

Answer 1

You can use _.merge() method from Lodash.

 let myObject = { id: 1, configs: { track: true, pulse: false }, name: 'slider', position: 1 } var update = _.merge({}, myObject, { name: 'scroller', configs: {} }) console.log(update) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script> 

Answer 2

 let myObject = { id: 1, configs: { track: true, pulse: false }, name: 'slider', position: 1 } let updatedObject = shallowAssignNonEmptyProperties(Object.assign({}, myObject), { name: 'scroller', configs: {} })) function shallowAssignNonEmptyProperties(target, source) { for (const prop in source) { const newValue = source[prop] if (typeof newValue !== 'object' || Object.keys(newValue).length) { target[prop] = newValue } } } 

When we want to skip specific properties, Object.assign() or object spread won't work. If you want to come up with a solution, it requires to iterate the properties, inspect the type of them and decide if you want that value to be assigned over.

• typeof newValue !== 'object' : we let pass values other than objects;
• Object.keys(newValue).length : check if the object is empty or have any properties;

This one is pretty simple, although if you need deep assignment/merge, you'll use a lib (lodash) or recursively call this function. It's up to you.

Answer 3

Nested properties are used as-is, they are not recursively assigned/merged. So the configs object is taken from the final argument of the assign(...) call (which is an empty object) and completely overrides the earlier values.