How to write a swap function in javascript (variable name as string input) [duplicate]

Question

For example,

x = 1;
y = 2;
swap ('x', 'y');
console.log (x); // 2
console.log (y); // 1

The swapped value may be not a simple variable

How to swap two variables in JavaScript doesn't require to have a calling, so it differs from this question.

Solved. I didn't know that the ref of left of = is evaled before the right is calculated

The problem is that javascript can't use pointers and can't modify the variable by a reference to it. — David Archibald
– David Archibald, Commented Jan 11, 2017 at 6:01
I don't quite understand how using a string would help, but as it is now closed, I will drop it. — David Archibald
– David Archibald, Commented Jan 11, 2017 at 6:06

Nina Scholz · Accepted Answer · 2017-01-11 06:00:57Z

0

For global variables, you could use the window object with the names as key.

function swap(a, b) {
    var temp = window[a];
    window[a] = window[b];
    window[b] = temp;
}

var x = 1,
    y = 2;

swap ('x', 'y');
console.log (x); // 2
console.log (y); // 1

answered Jan 11, 2017 at 6:00

Nina Scholz

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3 Comments

l4m2 Over a year ago

But not for variables in function

Rajesh Dixit Over a year ago

Its a bad practice polluting window. Why would you suggest it. Also, this is a duplicate. We should not answer duplicates as most of the approaches have been answered and have comments/ explanations for better understanding

Nina Scholz Over a year ago

i think the question is for educational purpose, as this answer. in real working environment, the problem is not solvable, because of the limited usage.

MarmiK · Accepted Answer · 2017-01-11 09:59:46Z

0

Try this:

function swap(x, y) {
  return [y, x]
}

[x, y] = swap(x, y);

edited Jan 11, 2017 at 9:59

MarmiK

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answered Jan 11, 2017 at 5:59

pcu

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1 Comment

l4m2 Over a year ago

It changes the calling of swap

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