I just started using nodeJS and I am having some difficulties understanding the variable scope and referencing. For example in the code below, variable a will change/be overwritten even though the slice was made to variable b. My question is, how could I copy variable a into variable b without referencing it/overwriting variable a.
var a = ['a', 'b', 'c', 'd'];
var b = a;
b.splice(3,1);
console.log(a) //will display ['a', 'b', 'c'] instead of ['a', 'b', 'c', 'd']
Instead of using a library like Amit suggested, this can be done natively and without installing a huge library...
Using .slice() with no arguments
var a = ['a', 'b', 'c', 'd'];
var b = a.slice();
b.splice(3,1);
console.log(a);
When you set b = a, you are NOT creating a new array, you are only telling b to hold a reference to a. So a and b are actually referencing the same location in memory. .slice works by returning a entire new array.
The functionality you're looking for is know as deep clone or deep copy.
There are several ways to do this, for example you could use lodash:
var _ = require('lodash');
var a = ['a', 'b', 'c', 'd'];
var b = _.cloneDeep(a);
_.cloneDeep is meant for objects, which are a little trickier to clone.a = [{name: 'some name'}]; b = a.slice(); b[0].name = 'some other name'; console.log(a);). My answer is an overkill for the sample code, not for the question itself.Thanks for the help but I found the answer to my problem. If anyone comes by this post and has the same problem, you can find the solution here Nodejs: how to clone a object
