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zenparsing /
Last active Dec 30, 2015
Simplified algorithm for detection of strict-mode errors in ECMAScript 6.

A context object is associated with any AST node which may have "strictness". Each context has a strictness state: UNKOWN, STRICT, and NOT_STRICT. In order to account for arrow functions, parenthesized expressions are also assigned a context.

When a context C is pushed:

  • set C.parent to the current context object
  • set C.strictError to null
  • if C.parent.strict is STRICT
    • set C.strict to STRICT
  • else
    • set C.strict to UNKNOWN
zenparsing / Promise.js
Created Dec 28, 2013
Minimal ES6 Promise
View Promise.js
function enqueueMicrotask(fn) {
// Enqueue a function on the System-defined FIFO
// microtask queue.
var $status = "Promise#status",
$value = "Promise#value",
$onResolve = "Promise#onResolve",
$onReject = "Promise#onReject";
zenparsing / async-io-1.js
Last active Aug 29, 2015
Reading and Writing Files with Async Generators
View async-io-1.js
This example uses an inner generator and skips over the first iteration in order to
prevent data loss which occurs on the first call to next.
import * as FS from "async-fs";
export function readFile(path) {
View measure-await.js
async function queueAlways() {
let x;
for (let i = 0; i < 100000; ++i)
x = await i;
async function queueIf() {
zenparsing / dedent-template.js
Last active Jan 16, 2020
Dedenting Template Strings
View dedent-template.js
function dedent(callSite, ...args) {
function format(str) {
let size = -1;
return str.replace(/\n(\s+)/g, (m, m1) => {
if (size < 0)
size = m1.replace(/\t/g, " ").length;
zenparsing /
Last active Aug 29, 2015
Abstract References for ECMAScript

Abstract References for ECMAScript

Overview and Motivation

Despite its functional programming facilities, ECMAScript exhibits a strong preference for object-oriented "left-to-right" composition using instance methods. Unfortunately, composition by means of instance methods requires that extensibility be achieved by adding function-valued properties to the object or a prototype ancestor of the object. This leads to the following difficulties:

View jquery-direct.js
(function($) { "use strict";
function wrap(method) {
return function() {
var jq = $(this),
result = jq[method].apply(jq, arguments);
if (result && result.constructor === $)
zenparsing / jake.js
Last active Aug 29, 2015
jQuery Reimagined
View jake.js
/* Redefine jQuery methods as "raw" methods */
(function($) { "use strict";
function wrap(method) {
return function() {
var jq = $(this),
result = jq[method].apply(jq, arguments);
zenparsing / optional-chaining-proxy.js
Last active Nov 22, 2018
Optional chaining with JS Proxy
View optional-chaining-proxy.js
const unwrapSymbol = Symbol();
function unwrap(x) {
if (this == null)
return this;
let f = this[unwrapSymbol];
if (typeof f !== "function")
You can’t perform that action at this time.