Reversing an array of objects in Javascript [duplicate]

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As the title says, I'd like to reverse an array made of objects in Javascript.

Example : var x = ["score":1,"score":2,"score":3]

var x = ["score":1,"score":2,"score":3]

To do so, I'm using the .reverse() method.

Now, let's say I write this code

console.log(x);
x.reverse();
console.log(x);


I'm expecting the console to show the array in the original order, then in a reversed order. However, It really shows both arrays in the reversed order.

How come ?

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3 Answers
3

console.log() takes into account whether a mutable object has changed before it has been printed on the screen. And as your process of OUTPUT -> CHANGE -> OUTPUT is almost plesiochronous, both outputs are the same. You have to use a copy of x in order to get the prompt you need.

console.log()

Try it this way:

// copy x
y = Object.assign(, x);
console.log(y);

x.reverse();
console.log(x);


best way to do that is:

var y = [...x].reverse();

var y = [...x].reverse();

var x = ["score":1,"score":2,"score":3]
console.log(x);
var y = [...x].reverse();
console.log(y);


I'm expecting the console to show the array in the original order, then in a reversed order. How come?

According to MDN here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reverse

The function reverse() is destructive

reverse()

it means, the function change the original array, you have to create another variable if you want store the original array like this:

var array1 = ['one', 'two', 'three'];
console.log('array1: ', array1);
// expected output: Array ['one', 'two', 'three']

var reversed = array1.reverse();
console.log('reversed: ', reversed);
// expected output: Array ['three', 'two', 'one']

/* Careful: reverse is destructive. It also changes
the original array */
console.log('array1: ', array1);
// expected output: Array ['three', 'two', 'one']