How to push a value but not a reference

Question

I want to push an array in the other array.I know concat() but what i want is not this.
Two dimensional array
perhaps:

    var a = [],b = [],c = [];
a.push(1);
b.push(a);
console.log(b);      //[[1]]
a.push(2);
console.log(b)       //[[1,2]]
a.push(3);           
console.log(b)       //[[1,2,3]]

b will be changed if a is changed,what i want is

 var a = [],b = [],c = [];
a.push(1);
b.push(a);
console.log(b)       //[[1]]
a.push(2);
console.log(b)       //[[1]]
a.push(3);           
console.log(b)       //[[1]]

Please [edit] your question to more clearly explain your desired result. What should `b` look like after the code runs? Are you saying you *don't* want a two-dimensional array? — nnnnnn, Jul 24 '17 at 03:38
You're not being clear at all, but I suspect you want `b.push(a.slice())`, it's still a reference of a value, but you'd get a copy of the array instead of the original. — adeneo, Jul 24 '17 at 03:39
https://stackoverflow.com/questions/3978492/javascript-fastest-way-to-duplicate-an-array-slice-vs-for-loop — epascarello, Jul 24 '17 at 03:47
I don't understand your use case. If you don't want the value to appear under `b` then just add a guard statement to preven it been added? — Samuel Toh, Jul 24 '17 at 04:05

score 1 · Accepted Answer · answered Jul 24 '17 at 04:04

1

You could point to a two dimension array like b[1][0].

you could use the following code to push an array values into another array

b.push(JSON.parse(JSON.stringify(a));

answered Jul 24 '17 at 04:04

fingerpich

8,500
2
22
32

yes , this is the correct,this is what i want, thank you – YXC.Coder Jul 24 '17 at 04:08

Trent · Answer 2 · 2017-07-24T16:55:39.983

0

To append array a onto array b, you can simply concatenate your arrays a and b together, as follows,

var a = a.concat(b);

or

var a = [].concat(a,b);

Both of these examples will return a combined array with all elements from both a and b.

edited Jul 24 '17 at 16:55

answered Jul 24 '17 at 03:41

Trent

4,208
5
24
46

Wouldn't `= a.concat(b)` do the same thing more concisely? – nnnnnn Jul 24 '17 at 03:43
Yes, but a lot of time someone may forget that you have to assign the results back to `a`. I'll update my answer. – Trent Jul 24 '17 at 16:53

How to push a value but not a reference

2 Answers2