Why is "5" + 2+3 and 2+3+ "5" different in JavaScript?

Question

This if giving me wrong result.

<p>The result of adding "5" + 2 + 3</p>

<p id="demo"></p>

<script>
  x = "5" + 2 + 3;
  document.getElementById("demo").innerHTML = x;
</script>

<p> result of adding 2+3+"5"</p>
<p id="qwe"></p>
<script>
  y = 2 + 3 + "5";
  document.getElementById("qwe").innerHTML = y;
</script>

Does this answer your question? [How does adding String with Integer work in JavaScript?](https://stackoverflow.com/questions/40848551/how-does-adding-string-with-integer-work-in-javascript) — kevinSpaceyIsKeyserSöze, Apr 22 '20 at 12:36

score 8 · Answer 1 · answered Apr 22 '20 at 12:28

+ evaluates left-to-right, so

"5" + 2+3

is equivalent to

("5" + 2) + 3

and the other one:

2+3+ "5"

is equivalent to:

(2 + 3) + "5"

When two numbers are +d together, they are added, so the result is a number. But if either side of the + is a string, the two expressions are concatenated instead of added. So

("5" + 2) + 3
// results in
'52' + 3
'523'

(2 + 3) + "5"
// results in
5 + '5'
55

Why is "5" + 2+3 and 2+3+ "5" different in JavaScript?

1 Answers1