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32 lines
833 B
32 lines
833 B
4 years ago
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'use strict';
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var common = require('./common');
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var EventEmitter = require('../');
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var assert = require('assert');
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var myEE = new EventEmitter();
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var m = 0;
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// This one comes last.
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myEE.on('foo', common.mustCall(function () {
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assert.strictEqual(m, 2);
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}));
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// This one comes second.
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myEE.prependListener('foo', common.mustCall(function () {
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assert.strictEqual(m++, 1);
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}));
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// This one comes first.
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myEE.prependOnceListener('foo',
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common.mustCall(function () {
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assert.strictEqual(m++, 0);
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}));
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myEE.emit('foo');
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// Verify that the listener must be a function
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assert.throws(function () {
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var ee = new EventEmitter();
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ee.prependOnceListener('foo', null);
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}, 'TypeError: The "listener" argument must be of type Function. Received type object');
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