How to use string inside a javascript selector inside a looping?

Question

I have form like this:

<form id="stuff">
<TEXTAREA name="roundkey1" id="roundkey1" rows="10" cols="40"></TEXTAREA>
<br>
Details R2 : ROund key 2 <BR>
<TEXTAREA name="roundkey2" id="roundkey2" rows="10" cols="40"></TEXTAREA>
<br>
Details R3 : ROund key 3 // <BR>
<TEXTAREA name="roundkey3" id="roundkey3" rows="10" cols="40"></TEXTAREA>
<br>
Details R4 : ROund key 4 // <BR>
<TEXTAREA name="roundkey4" id="roundkey4" rows="10" cols="40"></TEXTAREA>
<br>
Details R5 : ROund key 5 // <BR>
<TEXTAREA name="roundkey5" id="roundkey5" rows="10" cols="40"></TEXTAREA>
<br>
Details R6 : ROund key 6 // <BR>
<TEXTAREA name="roundkey6" id="roundkey6" rows="10" cols="40"></TEXTAREA>
<br>
Details R7 : ROund key 7 // <BR>
<TEXTAREA name="roundkey7" id="roundkey7" rows="10" cols="40"></TEXTAREA>
<br>
Details R8 : ROund key 8 // <BR>
<TEXTAREA name="roundkey8" id="roundkey8" rows="10" cols="40"></TEXTAREA>
<br>
Details R9 : ROund key 9 // *EUROBEAT INTENSIEF Stop<BR>
<TEXTAREA name="roundkey9" id="roundkey9" rows="10" cols="40"></TEXTAREA>
</form>

I have to select each textarea so i can insert a string which is inside accumulated_output_info variable;

i need to foreach that when i click a button using a loop like below:

for(var round = 1; round < 10;round++){
 document.stuff.roundkey+round.value = accumulated_output_info;
}

but i got an error like this:

(index):732 Uncaught ReferenceError: Invalid left-hand side in assignment

what could go wrong with my code ? how do i suppose to write that kind of string ?

`document.stuff.roundkey+round.value` is invalid, you can't do that before an assignment statement — Sterling Archer, Feb 28 '18 at 04:18
What do you mean by "selector"? What is this code supposed to do? — melpomene, Feb 28 '18 at 04:19
Try line by line. First do that `=` operation to `round.value`, then assign that what you have got to `document.stuff.roundkey`. `round` is a primitive and you are turning that into an object with `.value`. You will get `undefined` — Learn on hard way, Feb 28 '18 at 04:19
I don't know, I have no idea what you're trying to achieve here — Sterling Archer, Feb 28 '18 at 04:19
Possible duplicate of [Dynamically access object property using variable](https://stackoverflow.com/questions/4244896/dynamically-access-object-property-using-variable) — melpomene, Feb 28 '18 at 04:21
@SterlingArcher i have edited my question, please check it out — Gagantous, Feb 28 '18 at 05:04

Suresh Atta · Accepted Answer · 2018-02-28T05:09:43.913

Since you are trying use the property dynamically, use the square bracket notation, instead of . notation

document.forms.stuff['roundkey'+round].value = "Hello "+ round;

Edit :

for(var round = 1; round < 10;round++){
 debugger;
 document.forms.stuff['roundkey'+round].value = "Hello "+ round;

}

<form id="stuff">
<TEXTAREA name="roundkey1" id="roundkey1" rows="10" cols="40"></TEXTAREA>
<br>
Details R2 : ROund key 2 <BR>
<TEXTAREA name="roundkey2" id="roundkey2" rows="10" cols="40"></TEXTAREA>
<br>
Details R3 : ROund key 3 // <BR>
<TEXTAREA name="roundkey3" id="roundkey3" rows="10" cols="40"></TEXTAREA>
<br>
Details R4 : ROund key 4 // <BR>
<TEXTAREA name="roundkey4" id="roundkey4" rows="10" cols="40"></TEXTAREA>
<br>
Details R5 : ROund key 5 // <BR>
<TEXTAREA name="roundkey5" id="roundkey5" rows="10" cols="40"></TEXTAREA>
<br>
Details R6 : ROund key 6 // <BR>
<TEXTAREA name="roundkey6" id="roundkey6" rows="10" cols="40"></TEXTAREA>
<br>
Details R7 : ROund key 7 // <BR>
<TEXTAREA name="roundkey7" id="roundkey7" rows="10" cols="40"></TEXTAREA>
<br>
Details R8 : ROund key 8 // <BR>
<TEXTAREA name="roundkey8" id="roundkey8" rows="10" cols="40"></TEXTAREA>
<br>
Details R9 : ROund key 9 // *EUROBEAT INTENSIEF Stop<BR>
<TEXTAREA name="roundkey9" id="roundkey9" rows="10" cols="40"></TEXTAREA>
</form>

How to use string inside a javascript selector inside a looping?

1 Answers1