JavaScript: How can i set a variable in a string

Question

I would like to set attributes on all elements that id starts with "id-" followed by a number [e.g. id="id-0", id="id-1) and so on]. I thought about something like this:

<script type="text/javascript" >
function Prepare() {
 var = 0
 while(document.getElementById("id-{var}")) {
 document.getElementById("id-{var}").setAttribute("rows", "60");
 var += 1
 }
</script>

How can i set a var like this in JavaScript?

• Dennis Rongo: if (document.getElementById("id-"+variable)){ /** do stuff */};

Answer 1

this should accomplish the task:

<script type="text/javascript" >
function Prepare() {
 var ct = 0
 while(document.getElementById("id-"+ct)) {
 document.getElementById("id-"+ct).setAttribute("rows", "60");
 ct += 1
 }
</script>

alternatively:

<script type="text/javascript" >
function Prepare() {
 for(var ct = 0;document.getElementById("id-"+ct);ct++) {
 document.getElementById("id-"+ct).setAttribute("rows", "60");
 }
</script>

• ierdna: ct += 1 is equivalent to ct = ct + 1 or ct++
• T.J. Crowder: @ user: Gosh, really?!?!?!
• Shawn31313: @T.J.Crowder You learn something new everyday. Haha, but yeah. Its quite handy
• T.J. Crowder: @Shawn31313: My comment might have been sarcastic. ;-)

Answer 2

Depending on compatability you could use querySelectorAll():

function Prepare(){
 var els = document.querySelectorAll("[id^=id]");
 for(var i=0; i<els.length; i++){
 els[i].setAttribute("rows", 60);
 }
}

EXAMPLE