将除 javascript object 中的一个值外的每个元素值设置为 false

Question

I have an object like this:

layers = {a: false, b: false, c: false, d: false, e: false};
setLayer = (val) => {
   // set val to true and every other to false
}

I will call setLayer function on onClick event. Like this:

<a onClick={this.setLayer('c')}>hello</a>
// this will set layers like this: {a: false, b: false, c: true, d: 
false, e: false}
<a onClick={this.setLayer('b')}>hello world</a>
// this will set layers like this: {a: false, b: true, c: false, d: 
false, e: false}

I do not want to use for loop and check for each key in obj. Beacuse obj is adding more and more object in my code.

Answer 1

Take a variable

var lastUpdatedKey;

setLayer = (val) => {
    lastUpdatedKey && (layers[lastUpdatedKey] = false);
    layers[val] = true;
    lastUpdatedKey = val;
}

Answer 2

If you do not want to use a loop, you'll have to use a different implementation.

A very elegant solution is to use a Proxy in place of your layers object:

 const layers = new Proxy({}, { get: function(obj, prop) { return prop === obj.__active__; }, set: function(obj, prop, value) { if (!Object.getOwnPropertyDescriptor(obj, '__active__')) { Object.defineProperty(obj, '__active__', { value: null, writable: true, configurable: false, enumerable: false, }); } obj[prop] = false; if (value === true) { obj.__active__ = prop; } } }); layers.a = true; layers.b = false; layers.c = false; console.log(layers); layers.b = true; console.log(layers); layers.c = true; console.log(layers); 

Answer 3

i would suggest something likethis:

const initrnalValues = {a: false, b: false, c: false, d: false, e: false}
const layers = {a: false, b: false, c: false, d: false, e: false};

const setLayer = var => {
 Object.assign(layers, initrnalValues, {
    [val]: true
}
}

that's it, no loops of any kind

Answer 4

Use Object.keys to iterate over the keys in the layers object. If the key is matching with 'val', set it to true

layers = {a: false, b: false, c: false, d: false, e: false};
setLayer = (val) => {
 Object.keys(layers).forEach(item => {
   item == val ? layers[item] = true: ''
 })
}

Answer 5

Object.keys(object).forEach(key => object[key] = false)
object[oneKeyNeedToBeTrue] = true;