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tshemsedinovtshemsedinov
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Implement improved examples
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3 files changed

+253
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‎JavaScript/4-class.js

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'use strict';
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const DEFERRED_PENDING = 0;
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const DEFERRED_RESOLVED = 1;
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const DEFERRED_REJECTED = 2;
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class Deferred {
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constructor(onDone = null, onFail = null) {
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this.value = undefined;
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this.onDone = onDone;
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this.onFail = onFail;
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this.status = DEFERRED_PENDING;
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}
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isPending() {
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return this.status === DEFERRED_PENDING;
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}
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isResolved() {
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return this.status === DEFERRED_RESOLVED;
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}
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isRejected() {
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return this.status === DEFERRED_REJECTED;
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}
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done(callback) {
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this.onDone = callback;
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if (this.isResolved()) callback(this.value);
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return this;
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}
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fail(callback) {
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this.onFail = callback;
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if (this.isRejected()) callback(this.value);
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return this;
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}
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resolve(value) {
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this.value = value;
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if (this.onDone) this.onDone(value);
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return this;
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}
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reject(value) {
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this.value = value;
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if (this.onFail) this.onFail(value);
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return this;
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}
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}
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// Usage
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const persons = {
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10: 'Marcus Aurelius',
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11: 'Mao Zedong',
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12: 'Rene Descartes',
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};
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const getPerson = id => {
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const result = new Deferred();
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setTimeout(() => {
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const name = persons[id];
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if (name) result.resolve({ id, name });
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else result.reject(new Error('Person is not found'));
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}, 1000);
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return result;
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};
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const d1 = getPerson(10)
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.done(value => console.log('Resolved d1', value))
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.fail(error => console.log('Resolved d1', error));
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console.dir({ d1 });
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const d2 = getPerson(20)
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.done(value => console.log('Resolved d2', value))
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.fail(error => console.log('Resolved d2', error.message));
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console.dir({ d2 });

‎JavaScript/5-emitter.js

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'use strict';
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const { EventEmitter } = require('events');
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const DEFERRED_PENDING = 0;
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const DEFERRED_RESOLVED = 1;
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const DEFERRED_REJECTED = 2;
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class Deferred extends EventEmitter {
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constructor(onDone = null, onFail = null) {
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super();
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this.value = undefined;
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if (onDone) this.on('done', onDone);
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if (onFail) this.on('fail', onFail);
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this.status = DEFERRED_PENDING;
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}
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isPending() {
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return this.status === DEFERRED_PENDING;
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}
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isResolved() {
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return this.status === DEFERRED_RESOLVED;
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}
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isRejected() {
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return this.status === DEFERRED_REJECTED;
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}
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done(callback) {
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this.on('done', callback);
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if (this.isResolved()) callback(this.value);
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return this;
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}
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fail(callback) {
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this.on('fail', callback);
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if (this.isRejected()) callback(this.value);
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return this;
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}
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resolve(value) {
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this.value = value;
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this.emit('done', value);
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return this;
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}
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reject(value) {
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this.value = value;
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this.emit('fail', value);
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return this;
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}
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}
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// Usage
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const persons = {
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10: 'Marcus Aurelius',
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11: 'Mao Zedong',
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12: 'Rene Descartes',
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};
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const getPerson = id => {
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const result = new Deferred();
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setTimeout(() => {
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const name = persons[id];
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if (name) result.resolve({ id, name });
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else result.reject(new Error('Person is not found'));
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}, 1000);
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return result;
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};
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const d1 = getPerson(10)
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.done(value => console.log('Resolved d1', value))
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.fail(error => console.log('Resolved d1', error));
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console.dir({ d1 });
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const d2 = getPerson(20)
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.done(value => console.log('Resolved d2', value))
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.fail(error => console.log('Resolved d2', error.message));
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console.dir({ d2 });

‎JavaScript/6-promise.js

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'use strict';
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const { EventEmitter } = require('events');
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const DEFERRED_PENDING = 0;
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const DEFERRED_RESOLVED = 1;
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const DEFERRED_REJECTED = 2;
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class Deferred extends EventEmitter {
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constructor(onDone = null, onFail = null) {
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super();
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this.value = undefined;
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if (onDone) this.on('done', onDone);
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if (onFail) this.on('fail', onFail);
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this.status = DEFERRED_PENDING;
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}
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isPending() {
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return this.status === DEFERRED_PENDING;
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}
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isResolved() {
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return this.status === DEFERRED_RESOLVED;
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}
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isRejected() {
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return this.status === DEFERRED_REJECTED;
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}
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done(callback) {
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this.on('done', callback);
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if (this.isResolved()) callback(this.value);
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return this;
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}
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fail(callback) {
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this.on('fail', callback);
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if (this.isRejected()) callback(this.value);
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return this;
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}
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resolve(value) {
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this.value = value;
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this.emit('done', value);
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return this;
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}
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reject(value) {
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this.value = value;
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this.emit('fail', value);
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return this;
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}
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promise() {
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return new Promise((resolve, reject) => {
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this.on('done', value => resolve(value));
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this.on('fail', error => reject(error));
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});
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}
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}
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// Usage
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const persons = {
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10: 'Marcus Aurelius',
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11: 'Mao Zedong',
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12: 'Rene Descartes',
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};
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const getPerson = id => {
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const result = new Deferred();
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setTimeout(() => {
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const name = persons[id];
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if (name) result.resolve({ id, name });
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else result.reject(new Error('Person is not found'));
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}, 1000);
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return result;
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};
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(async () => {
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try {
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const value = await getPerson(10).promise();
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console.log('Resolved p1', value);
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} catch (e) {
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console.log('Rejected p1', e.message);
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}
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try {
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const value = await getPerson(20).promise();
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console.log('Resolved p2', value);
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} catch (e) {
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console.log('Rejected p2', e.message);
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}
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})();

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