Im trying to replace a particular char within an index of an array.

Question

Im trying to replace the first '0' in index 0 of the array I made called 'bits'.

bits = ['01010'];

console.log(bits[0].charAt(1));

bits[0].charAt(0) = '9'; // <-Not working

console.log(bits[0].charAt(0));

What would I replace the third line of code with above to accomplish this?

The final console log should return '9'

(JSBIN link)

Also str.replaceAt doesnt work as well

Possible duplicate of [How do I replace a character at a particular index in JavaScript?](https://stackoverflow.com/questions/1431094/how-do-i-replace-a-character-at-a-particular-index-in-javascript) — juvian, Feb 08 '18 at 20:58
Strings are immutable. Even if that statement had been `bits[0][0] = '9'`, the assignment would have been a no-op in non-strict mode and thrown a `TypeError` in strict mode. — Patrick Roberts, Feb 08 '18 at 20:59
charAt is a function that return a value. You cannot assign a value to it. — floverdevel, Feb 08 '18 at 21:00
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String#Character_access — axiac, Feb 08 '18 at 21:02

Jonas Wilms · Answer 1 · 2018-02-08T21:06:51.577

4

 bits[0] = "9" + bits[0].substr(1);

Alternatively you can write a replace function:

function replace(str, replace, start, end){
  return str.substr(0, start) + replace + str.substr(end || start + replace.length);
}

bits[0] = replace(bits[0], "9", 0);

edited Feb 08 '18 at 21:06

answered Feb 08 '18 at 20:57

Jonas Wilms

132,000
20
149
151

score 2 · Answer 2 · answered Feb 08 '18 at 21:16

make a copy of string to replace any character . also a custom function "setCharAt" needs to be defined

function setCharAt(str,index,chr) {
    if(index > str.length-1) return str;
    return str.substr(0,index) + chr + str.substr(index+1);
}

after declaring the functions execute below given code to replace character at "0" index

bits[0]=setCharAt(bits[0],0,9)

after doing this final console.log will return "9"

score 1 · Accepted Answer · answered Feb 08 '18 at 21:01

1

var bits = ['01010'];
console.log(bits); //["01010"]
bits[0] = bits[0].replace('0','9');
console.log(bits); //["91010"]

answered Feb 08 '18 at 21:01

Bassem Rabia

206
2
7

4

That would not guarantee the 0th index being replaced if the `bits` string was a different value. – Patrick Roberts Feb 08 '18 at 21:02

Im trying to replace a particular char within an index of an array.

3 Answers3