The throw()
method resumes the execution of a generator by throwing an error into it and returns an object with two properties done
and value
.
Generator.prototype.throw()
Syntax
throw(exception)
Parameters
-
exception
-
The exception to throw. For debugging purposes, it is useful to make it an
instanceof
Error
.
Return value
An Object
with two properties:
-
done
-
A boolean value:
-
true
if the iterator is past the end of the iterated sequence. In this casevalue
optionally specifies the return value of the iterator. -
false
if the iterator was able to produce the next value in the sequence. This is equivalent to not specifying thedone
property altogether.
-
-
value
-
Any JavaScript value returned by the iterator. Can be omitted when
done
is true.
Examples
Using throw()
The following example shows a simple generator and an error that is thrown using the throw
method. An error can be caught by a try...catch
block as usual.
function* gen() { while(true) { try { yield 42; } catch(e) { console.log('Error caught!'); } } } const g = gen(); g.next(); // { value: 42, done: false } g.throw(new Error('Something went wrong')); // "Error caught!" // { value: 42, done: false }
Specifications
Browser compatibility
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
throw |
39
|
13
|
26
|
No
|
26
|
10
|
39
|
39
|
26
|
26
|
10
|
4.0
|
1.0
|
4.0.0
0.12.0
|
See also
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator/throw