How to change text of button onclick?

Question

Hello everyone, I want to change the text of a button when he is clicked. When he has prefix [+] change it to [-] else [+]. So I did this not-working attempt:

<button id="operators_c" class="collapsible" onclick="col(this.id)">[+]Operators</button>
<script>
function Col(i) {
var o = Document.getElementById(i);
var sub1 = o.textContent.substring(0,4);
if (sub1 == "[+]") {
o.textContent = "[-]" & o.textContent;
}
if (sub1 == "[-]") {
o.textContent = "[+]" & o.textContent;
}
}
</script>

Answer 1

1. JavaScript is CaSe SeNsItIve language. So col and Col is a different functions (if you see javascript errors, you will get something about "undefined function col"). And also "document", not "Document"
2. What do you mean by "&" operator? If you want to concatenate strings, than use "+" operator. "[-]" + o.textContent;
3. If you want to CHANGE [-] to [+] and [+] to [-], then you must write: "[-]" + o.textContent.substring(3). This will concatenate the "[-]" to button text without a first "[+]"
4. Why you do substring(0, 4)? Length of "[-]" and "[+]" is 3 letters.

Complete working code:
https://code.sololearn.com/W5YqSjXTUs4n/#js

Answer 2

Oh
Am sorry Stanislav Vladev
Didn't get the question
See TurtleShell Code
Thanks Mishin870

Answer 3

https://code.sololearn.com/Wfpv5V8Vi3ve/?ref=app

Answer 4

- Col() function in the script is uppercase in the button onclick attribute it’s lowercase change one of those
- Document object is uppercase, it’s lowercase so document.getElementById()
- substring(0, 4) will get “[+]O” change it to (0, 3)
- No need to use the & bitwise operator simply doing “[-]Operators” and “[+]Operators” will be fine

Optional
- Instead of passing the id just pass the object (this) it saves you fom doing document.getElementById()

My version: https://code.sololearn.com/W5DxXoHMTcSs/?ref=app

Answer 5

Ishola, he needs both "[+]/[-]" and the text on the button, but you just replace this text.