I have two objects:
let first = {
a: 'John',
b: 22,
c: 'example'
}
let second = {
b: 55,
d: 'demo'
}
I want to replace only already existing items from second object to first one. Result should look like this (so only b item should be changed, and new d item ignored):
{
a: 'John',
b: 55, // changed
c: 'example'
}
Merge will not work because it will add also new item. I can use foreach but I believe that there should be shorted answer for this. I'm already using lodash in my project so I can use function from there, but I cannot find any for this purpose. Is there any?
如果使用ES6,则可以使用它
let merge = { ...first, ..._.pick(second, Object.keys(first)) }
You can use a loop over the keys in the second array. For any keys that exist in the first, overwrite the value.
let first = { a: 'John', b: 22, c: 'example' } let second = { b: 55, d: 'demo' } for (const k in second) { if (k in first) { first[k] = second[k]; } } console.log(first);
With lodash you could do something like this with _.merge
, _.pick
and _.keys
:
let first = { a: 'John', b: 22, c: 'example' }, second = { b: 55, d: 'demo' } let result = _.merge(first, _.pick(second, _.keys(first))) console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
With ES6 you can use Object.keys and then Array.forEach on a new object like this:
let first = { a: 'John', b: 22, c: 'example' }, second = { b: 55, d: 'demo' }, result = new Object(null) Object.keys(first).forEach(k => result[k] = second[k] || first[k]) console.log(result)
This assumes you do not want to mutate
any of the objects. IF you do not care:
let first = { a: 'John', b: 22, c: 'example' }, second = { b: 55, d: 'demo' } Object.keys(first).forEach(k => first[k] = second[k] || first[k]) console.log(first)
You want to update the values of the
intersection
of the properties.
So basically something like:
Object.keys(a).forEach(prop => if(b.hasOwnProperty(prop)) a[prop] = b[prop]))
Or
_.intersection(Object.keys(a), Object.keys(b)).forEach(prop => a[prop] = b[prop])
let first = { a: 'John', b: 22, c: 'example' } let second = { b: 55, d: 'demo' } Object.keys(second).forEach(function(key,index){ if (first.hasOwnProperty(key)) { first[key]=second[key]; } }); console.log(first);
With Lodash two functions MergeWith and Pick
var a = {
a: 'John',
b: 22,
f:[11,22,2],
d: {a:1,b:2,c:0},
c: 'example'
}
var b = {
b: 55,
f:[3],
d: {c:1,b:11},
}
function mergeObjects(a,b){
let common = _.pick(b, Object.keys(a));
return _.mergeWith(a, common, customizer)
}
function customizer(objValue, srcValue) {
if (_.isArray(objValue)) {
return objValue.concat(srcValue);
}
if(_.isObject(objValue)) {
return mergeObjects(objValue,srcValue)
}
}
mergeObjects(a,b)
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.