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Clone Object with arrays using spread operator


Clone Object with arrays using spread operator

By : Frank Nowinski
Date : November 18 2020, 03:01 PM
help you fix your problem Object.assign and the spread operator create shallow clones, only one level deep, beyond that they are referenced. The best way I've found ( MDN) is to use JSON functions to create a true clone.
code :
let vehicles = { 
  cars:  [1, 2],
  boats: [3, 4],
};

let test = JSON.parse(JSON.stringify(vehicles));

console.log(vehicles, test);

test.cars[0] = 5;
vehicles.cars[0] = 7;

console.log(vehicles, test);


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Js spread operator and nested arrays

Js spread operator and nested arrays


By : Tee
Date : March 29 2020, 07:55 AM
will be helpful for those in need What you forgot is reassembling the line array properly. Try breaking it down like this:
code :
const changedElement = {
    ...state.line[lineIndex],
    media: [
        ...state.line[lineIndex].media.slice(0, action.payload.index),
        ...state.line[line_index].media.slice(action.payload.index + 1)
    ]
}

return {
    ...state,
    line: [
        ...state.line.slice(0, line_index),
        changedElement,
        ...state.line.slice(line_index + 1)
    ]
}
state = {
    line: [
        {
            media: []
        },
        {
            media: []
        }
    ]
}
What is the reason for not spread (es 6 spread operator) javascript Error object

What is the reason for not spread (es 6 spread operator) javascript Error object


By : Urim Sadiku
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , This is because the spread syntax in object literals "copies own enumerable properties from a provided object onto a new object".
None of the own properties of your Error object are enumerable.
code :
var error = new Error('error');
var props = Object.getOwnPropertyDescriptors(error);
console.log(props); // none of these are enumerable
var error = new Error('error');
error.foo = 'bar';
console.log({...error});
Lodash Clone Array vs Spread Operator

Lodash Clone Array vs Spread Operator


By : user3362284
Date : March 29 2020, 07:55 AM
may help you . It looks like clone is faster than the spread operator: https://www.measurethat.net/Benchmarks/ShowResult/81691 .
However, as javascript in an expensive resource to process, it's probably not a good idea to add a library to do what vanilla js can do perfectly well.
How do I enable spread operator with plugin-proposal-object-rest-spread in Babel 7?

How do I enable spread operator with plugin-proposal-object-rest-spread in Babel 7?


By : Rohini Srivathsa
Date : March 29 2020, 07:55 AM
Any of those help NOTE: I'm using Quasar framework, so my instructions may be very slightly different, but is mostly the same.
For the others like me who were spending hours on this issue that shouldn't have been in the first place, here's how I solved it:
code :
module.exports = {
    "plugins": [
      "@babel/plugin-proposal-object-rest-spread"
    ]
}
JS clone objects using spread operator and change one field

JS clone objects using spread operator and change one field


By : L J
Date : October 13 2020, 12:00 AM
it helps some times You spread syntax on right hand side.
Note: Use Spread Operator first then set the new property. For example {c:'D',...foo} will not work.
code :
let foo = {a: 'A', b: 'B', c: 'C'};
let res = {...foo, c:'D'};
console.log(res)
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