Passing a variable to another function in Javascript

Question

I asked a question a while back about how to get the current variable in a loop and I got the solution :

 for (i in ...)
 {
 ...
 href:"javascript:on_click('+i+');"...}

When i run this, the loop is sending the on_click function the string 'i' instead of the value of i.
Am I using the +variable+ wrong? Can someone explain in more detail what wrapping a variable in + means and why it is not working in my case?

Answer 1

Yes, you are - if you start a string with ", you have to end it with " (and vice versa for '), too. The syntax highlighting here at SO demonstrates this quite well too.

 href:"javascript:on_click("+i+");"...}

(What is happening is that ' within a string surrounded by " is treated as regular ' character, it does not start nor end a string literal here).

• Linens: what is it called when i do +i+? I'd like to look up more information on it except I don't know what to search up
• Alexander Gessler: What happens is that i is converted to a string and concatenated to the surrounding strings.

Answer 2

Try this:

href:"javascript:on_click('" + i + "');"

• Linens: YESSS thank you so much! I've been trying to figure this out for so longggg. Could you explain why this works?
• Mārtiņš Briedis: Look at this tutorial: quirksmode.org/js/strings.html pretty neat code examples there, that should give you the right idea.

Answer 3

Appears that you are missing double quotes to close your string. Javascript doesn't do variable interpolation in a quoted string.

Try:

href:"javascript:on_click('" + i + "');"...}

Answer 4

You're mixing your quote marks.

It should be:

href: "javascript:on_click('" + i + "');"

Note how the double quotes are necessary at both ends of the invariant parts.