function assert.ifError
Usage in Deno
import assert from "node:assert";
ifError(value: unknown): asserts value is null | undefined
Throws value if value is not undefined or null. This is useful when
testing the error argument in callbacks. The stack trace contains all frames
from the error passed to ifError() including the potential new frames for ifError() itself.
import assert from 'node:assert/strict';
assert.ifError(null);
// OK
assert.ifError(0);
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 0
assert.ifError('error');
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 'error'
assert.ifError(new Error());
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: Error
// Create some random error frames.
let err;
(function errorFrame() {
err = new Error('test error');
})();
(function ifErrorFrame() {
assert.ifError(err);
})();
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: test error
// at ifErrorFrame
// at errorFrame
asserts value is null | undefined