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javascript purpose of semicolon?
dumb question
mongoloid001




msg:1489239
 7:30 pm on Aug 6, 2003 (gmt 0)


Hi,

Never realized this before. A javascript expression doesn't have to end with a ';'.

So what's the diffrence? For example, between
alert("1") & alert("1");

This kind of things are so hard to find through search engines:).

 

SethCall




msg:1489240
 7:37 pm on Aug 6, 2003 (gmt 0)

it programming, one usually indicates the end of a statement with a semi-colon. Some langauges, such as c or c++, demand it.

Javascript, on the other hand, does not demand it, so if you don't want to put it, then don't.

tedster




msg:1489241
 8:07 pm on Aug 6, 2003 (gmt 0)

When writing or editing javascript, the semicolon helps a lot visually.

Depending on your editor, it may not be clear otherwise if you actually have a line break in there (ending the line of code). Instead, your editor may just be wrapping the line visually. So without the semicolon, you can make and overlook errors more easily.

MonkeeSage




msg:1489242
 10:18 pm on Aug 6, 2003 (gmt 0)

Semicolen is a formally necessary part of JavaScript statements:

[mozilla.org...]
[mozilla.org...]

Practically speaking, it is not needed in most cases. The browser can usually parse statements based on new-lines, line-breaks and other informal conventions.

It is a good idea to put it anyways, though, because for example, a person may have the option to use strict JS in Mozilla turned on, and they might get syntax warnings in the console without it.

Also, in certain cases (e.g., in a bookmarklet) the lack of the semicolen may cause the evaluation of the statement to fail because there is no new-line or space or line-break between two statements (e.g., var a="Henry the ",b=7;++b;alert(a+b+"th\nI am, I am...");).

Jordan

g1smd




msg:1489243
 10:23 pm on Aug 6, 2003 (gmt 0)

If you have multiple, or nested, IF ... THEN ... ELSE statements and you miss off a semi-colon then the code may do something different to what you were expecting in some browsers.

MonkeeSage




msg:1489244
 10:36 pm on Aug 6, 2003 (gmt 0)

g1smd:

I had something similar happen just the other day actually, lol. I switch()'d a value and in one of the cases I forgot the semicolen after the break statement, doh. Took me like an hour to figure out what was wrong with it.

Jordan

gph




msg:1489245
 10:45 pm on Aug 6, 2003 (gmt 0)

MonkeeSage I did exactly the same thing a couple weeks ago :) I stared at it for ages. I'm not condoning it but I only use semicolons if I have to. It's a bad habit that shows up in things like switch()

photon




msg:1489246
 12:59 pm on Aug 7, 2003 (gmt 0)

I believe they're also required if you have more than one statement per line. (for those who like to eliminate all possible redundant whitespace to reduce file sizes)

korkus2000




msg:1489247
 1:29 pm on Aug 7, 2003 (gmt 0)

It is required for multiple statements on one line. If you want to save space by combining lines then the semicolon lets the parser know it is a new statement. On some browsers the semicolon is required for multiple commands inside of one command structure.

if(y=0){
alert("yes");
y=1;
}

Some parsers need the semicolon or you get an error because it runs the to statements together.

wkitty42




msg:1489248
 3:42 pm on Aug 7, 2003 (gmt 0)

korkus,

what space are you saving? in your example, at worst case, you're only saving 6 or 9 bytes (3 CRLF pairs and maybe 3 space characters)...

killroy




msg:1489249
 3:49 pm on Aug 7, 2003 (gmt 0)

I think that'd be visual space, i.e. line count

SN

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