Google app script : New variable keeps reference of source variable

Question

We have variable "a" and we want to create variable "b" as a mirror of "a" variable and then change one of its elements.

Code

function h(){
var a=[[1,2,3]]
var b=a;
b[0][0]="test"
Logger.log(b)
Logger.log(a)
}

Output

[[test,2,3]]
[[test,2,3]]

Why is this happening? Any way to avoid this?

score 1 · Accepted Answer · edited May 23 '17 at 11:54

1

This referes to another question:

You may test some suggested solutions. I've tested this answer:

The code:

function h(){
  var a=[[1,2,3]];
  var b = JSON.parse(JSON.stringify(a));
  b[0][0]="test";
  Logger.log(b);
  Logger.log(a);
}

result is

[[test, 2, 3]]
[[1.0, 2.0, 3.0]

Looks like, javascript like c does not do array assignments.

edited May 23 '17 at 11:54

Community

answered Apr 11 '17 at 12:12

Max Makhrov

I made a function using you suggestion and worked fluently everywhere in my project. Thank you a lot. – Jason Tragakis Apr 11 '17 at 20:45

score 0 · Answer 2 · answered Apr 11 '17 at 13:12

0

You have to deep copy value in array b for this you can use slice method :

arr2 = arr1.slice();

Below is your code with some modifications:

function h(){
var a=[1,2,3];
var b= a.slice();
b[0]="test";
console.log(b);
console.log(a);
}

answered Apr 11 '17 at 13:12

Ayush

Thank you but as I was using arrays and objects Max's solution worked better. – Jason Tragakis Apr 11 '17 at 21:06

2 Answers2