Is there something like "die" in JavaScript? I've tried with "break", but doesn't work :)
15 Answers
throw new Error("my error message");
5 Comments
Alexar
this is absolutely the answer and works just like die(); however one should not care for the red "1 Error" of firebug!
Adrian Maire
I think that if PHP has a "firebug" equivalent, it should also write "1 error" on die() ;-) Good answer!
Stas Bichenko
Won't this produce a warning dialog box in IE8?
Brilliand
Not a 1-to-1 equivalent, since PHP has uncaught exceptions too.
Rolf
This will not totally stop execution AFAIK, but only roughly around the throw. Specifics are very blurry but I'm pretty sure the script can keep running somewhere else.
You can only break a block scope if you label it. For example:
myBlock: {
var a = 0;
break myBlock;
a = 1; // this is never run
};
a === 0;
You cannot break a block scope from within a function in the scope. This means you can't do stuff like:
foo: { // this doesn't work
(function() {
break foo;
}());
}
You can do something similar though with functions:
function myFunction() {myFunction:{
// you can now use break myFunction; instead of return;
}}
3 Comments
enchance
I never knew about labelling a block scope much less writing a block scope. Does it mean that
foo: {} is an object?
Eli Grey
No. It's a block scope. It's the same as
foo: if(true){...}
bb216b3acfd8f72cbc8f899d4d6963
Is there any alternative since you can't "break a block scope from within a function in the scope"?
You can simply use the return; example
$(document).ready(function () {
alert(1);
return;
alert(2);
alert(3);
alert(4);
});
The return will return to the main caller function test1(); and continue from there to test3();
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<script type="text/javascript">
function test1(){
test2();
test3();
}
function test2(){
alert(2);
return;
test4();
test5();
}
function test3(){
alert(3);
}
function test4(){
alert(4);
}
function test5(){
alert(5);
}
test1();
</script>
</body>
</html>
but if you just add throw ''; this will completely stop the execution without causing any errors.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<script type="text/javascript">
function test1(){
test2();
test3();
}
function test2(){
alert(2);
throw '';
test4();
test5();
}
function test3(){
alert(3);
}
function test4(){
alert(4);
}
function test5(){
alert(5);
}
test1();
</script>
</body>
</html>
This is tested with firefox and chrome. I don't know how this is handled by IE or Safari
3 Comments
André Leria
As far as I know,
return exits only the enclosing function. It does not work when you want to stop executing the whole script.
themhz
hmmm yes you are right, it does not stop the execution of all the script.
FZs
throw "": ...without causing any errors... - Not quite... Uncaught ""Just call die() without ever defining it. Your script will crash. :)
When I do this, I usually call discombobulate() instead, but the principle is the same.
(Actually, what this does is throw a ReferenceError, making it roughly the same as spudly's answer - but it's shorter to type, for debugging purposes.)
3 Comments
Beejor
The use of a custom undefined identifier is very creative! I like how
die is intuitive and concise. It does lack the benefit of throw when it comes to logging a specific error message, but sometimes just the line number is enough. BTW, die; without the parentheses (un-)works too.
MarcoZen
or just die; at the line where you want your javascript to stop.
Yonn Trimoreau
This answer is so JS minded^^ It's not dirty if it works!
If you're using nodejs, you can use
process.exit(<code>);
you can try with :
return;
that work in case of stop process.
Comments
It is possible to roll your own version of PHP's die:
function die(msg)
{
throw msg;
}
function test(arg1)
{
arg1 = arg1 || die("arg1 is missing");
}
test();
2 Comments
Dmytro
I wanted to mention that this won't work in cases like
var a = arguments[3] || die('message'). instead, I think die should be: function die(msg) { return eval(`throw "${msg}"`);) but even then, I think this should just be hard placed on the line that breaks so that the error shows which line failed, eg this.inputFile = argv[2] || eval('throw "this program requires an input file."');
Kelmar
Probably, not sure eval() solves the problem if I'm understanding you. Ideally one would be looking at a stack trace if you were interested in where a failure was actually ocuring. Otherwise I would think it's safe to assume that you simply want to report some sort of basic failure message tor your user.
There is no function exit equivalent to php die() in JS, if you are not using any function then you can simply use return;
return;
Comments
Global die() function for development purposes:
var die = function(msg) {
throw new Error(msg);
}
Use die():
die('Error message here');
Comments
There's no exact equaliant of language construct die of PHP in Javascript. die in PHP is pretty much equal to System.exit() in Java, which terminates the current script and calls shutdown hooks.
As some users suggested; throw Error can be used in some cases, however it never guarantees the termination of the current script.
There can be always an exception handling block surrounding your throw statement- unless you call it on the top most level script block, which eventually exits only the script block you're executing.
However it won't prevent the second block from being executed here (prints hello):
<script type="text/javascript">
throw new Error('test');
</script>
<script type="text/javascript">
document.write("hello");
</script>
Comments
You can use return false; This will terminate your script.
2 Comments
Rolf
Only at the top level, presumably. PHP's die() can be called at any level and will cause the PHP interpreter to go away right there.
This should kind of work like die();
function die(msg = ''){
if(msg){
document.getElementsByTagName('html')[0].innerHTML = msg;
}else{
document.open();
document.write(msg);
document.close();
}
throw msg;
}
Comments
One way is to add all of your code in an anonymous function
( () => {
//this is the whole body
if( iWantToDie ) return;
}
)()This looks a lot cleaner to me than throwing errors
Comments
<script>
alert("i am ajith fan");
<?php die(); ?>
alert("i love boxing");
alert("i love MMA");
</script>
1 Comment
A4tur
nah man this another level of comedy 🤣
function die(str) {throw new Error(str || "Script ended by death");}Or something XD Plenty of better options out there, but this would work. Might be good for debugging, if you only want to run the first part of a script to make sure it works.die,goto,eval, etc. are endlessly regurgitated (and not without merit), but they all have their special uses, especially for low-level debugging. Otherwise languages wouldn't include them. In this case, the JS equivalents ofreturnandthroware innocuous enough.