How to convert Nodejs counter readable stream example to simplified construction version? - javascript

I refer to this doc
https://nodejs.org/api/stream.html#simplified-construction
The _construct() method is never called in my version. Why?
Note: In simplified construction you provide the implementation of _construct() method in the constructor options {construct() {...}, ...}
This is a working class version of a readable stream counter example:
const { Readable } = require('stream');
class Counter extends Readable {
constructor(options) {
super(options);
this._max = 10;
this._index = 1;
}
_read() {
const i = this._index++;
if (i > this._max) {
this.push(null);
} else {
const str = String(i);
const buf = Buffer.from(str, 'utf-8');
this.push(buf);
}
}
}
const readable = new Counter();
readable.on('readable', function() {
console.log('readable');
let data;
while ((data = this.read()) !== null) {
console.log(String(data));
}
});
readable.on('close', function() {
console.log('close');
});
This is my not working simplified construction version:
const { Readable } = require('stream');
const counter = new Readable({
construct() {
this._max = 10;
this._index = 1;
console.log(this._max); // This is never executed
},
read() {
console.log(this._max); // This is undefined
this.push(null);
}
// read() {
// const i = this._index++;
// if (i > this._max) {
// this.push(null);
// } else {
// const str = String(i);
// const buf = Buffer.from(str, 'utf-8');
// this.push(buf);
// }
// }
});
counter.on('readable', function() {
let data;
while ((data = this.read()) !== null) {
console.log(String(data));
}
});
counter.on('close', function() {
console.log('close');
});
The docs say:
const { Writable } = require('node:stream');
const myWritable = new Writable({
construct(callback) {
// Initialize state and load resources...
},
write(chunk, encoding, callback) {
// ...
},
destroy() {
// Free resources...
}
});
Now I'm confused. Thought initialization code belongs into the _construct() method?

As stated in my comment above, _construct()is added in Node Version 15.x. For further reference, follows the working example:
const { Readable } = require('stream');
const counter = new Readable({
construct(callback) {
this._max = 10;
this._index = 1;
callback(); // Signal completion of initialization
},
read() {
const i = this._index++;
if (i > this._max) {
this.push(null);
} else {
const str = String(i);
const buf = Buffer.from(str, 'utf-8');
this.push(buf);
}
}
});
counter.on('readable', function() {
let data;
while ((data = this.read()) !== null) {
console.log(String(data));
}
});
counter.on('close', function() {
console.log('close');
});

Related

javascript multiple function callback syntax

I can't wrap my head around callback syntax, can you please help me re-write my code so that it executes in this order:
MenuBuilder.load()
MenuBuilder.draw()
Translator.load()
(in my case it executes in this order MenuBuilder.load(), Translator.load(), MenuBuilder.draw() so it doesn't do what I want)
onload.js
import MenuBuilder from "./menu-builder.js";
import Translator from "./translator.js";
var menuBuilder = new MenuBuilder();
var translator = new Translator();
menuBuilder.load();
translator.load();
menu-builder.js
"use strict"
class MenuBuilder {
constructor() {
this._nav = document.getElementsByTagName("nav")[0];
this._url = window.location.href;
}
load() {
console.log("MenuBuilder.load() start");
fetch(`/json/menu.json`)
.then((res) => res.json())
.then((jsonMenu) => {
this.draw(jsonMenu);
})
/*.catch(() => {
console.error(`Could not load ${this._lang}.json.`);
});*/
console.log("MenuBuilder.load() end");
}
draw(jsonMenu) {
console.log("MenuBuilder.draw(jsonMenu) start");
var htmlMenu = `<div id="siteTitleDiv"><p id="siteTitle" data-i18n="general.title"></p><p id="siteTitleShadow" data-i18n="general.title-shadow"></p><p id="siteSubtitle"data-i18n="general.subtitle"></p></div><ul>`;
for(var i = 0; i < jsonMenu.length; i++) {
var menuItem = jsonMenu[i];
var regexp = /http:\/\/cypher-f\.com\/(([a-z\-]*\/)?([a-z\-]*\/))?/g;
var fullPage = "something format_abc";
var match = regexp.exec(this._url);
var level_1 = match[1];
var level_2 = match[3];
var parent = match[2];
var full_suffix = match[0];
if ((parent == null) || (menuItem.parent === parent)) {
var material_icon = menuItem["material-icon"];
var href = menuItem["href"];
var i18n = menuItem["data-i18n"];
htmlMenu += `<li><i class="material-icons">${material_icon}</i></li>`;
}
}
htmlMenu += `</ul>`;
this._nav.innerHTML = htmlMenu;
console.log("MenuBuilder: nav.innerHTML");
console.log(this._nav.innerHTML);
console.log("MenuBuilder: document.elements");
console.log(document.querySelectorAll("[data-i18n]"));
console.log("MenuBuilder.draw(jsonMenu) end");
}
}
export default MenuBuilder;
translator.js
"use strict"
class Translator {
constructor() {
this._lang = this.getLanguage();
this._elements = document.querySelectorAll("[data-i18n]");
}
getLanguage() {
var lang = navigator.languages ? navigator.languages[0] : navigator.language;
return lang.substr(0, 2);
}
load(lang = null) {
console.log("Translator.load() start");
console.log("this._elements");
console.log(this._elements);
if (lang) {
this._lang = lang;
}
else {
var re = new RegExp("lang=([^;]+)");
var value = re.exec(document.cookie);
var cookieLang = (value != null) ? unescape(value[1]) : null;
if (cookieLang) {
this._lang = cookieLang;
}
}
fetch(`/i18n/${this._lang}.json`)
.then((res) => res.json())
.then((translation) => {
this.translate(translation);
})
.then(this.toggleLangTag())
.then(document.cookie = `lang=${this._lang};path=/`)
/*.catch(() => {
console.error(`Could not load ${this._lang}.json.`);
});*/
console.log("Translator.load() end");
}
translate(translation) {
console.log("Translator.load(translation) start");
this._elements.forEach((element) => {
var keys = element.dataset.i18n.split(".");
var text = keys.reduce((obj, i) => obj[i], translation);
if (text) {
element.innerHTML = text;
}
else {
element.innerHTML = `key ${keys} not found for ${this._lang}!`
}
});
console.log("Translator.load(translation) end");
}
toggleLangTag() {
if (document.documentElement.lang !== this._lang) {
document.documentElement.lang = this._lang;
}
}
switchLanguage(translator) {
var availableLang = ["en", "fr"];
var currentLangIndex = availableLang.indexOf(translator._lang);
var nextLang = availableLang[(currentLangIndex + 1)%availableLang.length];
translator.load(nextLang);
}
}
export default Translator;
I'm sorry I know this is kind of a newbie question but I haven't programmed in three years.
You're working with Promises here, so you want to stick with that paradigm. Return the promise that is returned from the fetch call, then "chain" off of that promise to call the translator.
load() {
console.log("MenuBuilder.load() start");
// The return here gives control of the promise to the caller...
return fetch(`/json/menu.json`)
.then((res) => res.json())
.then((jsonMenu) => {
this.draw(jsonMenu);
})
/*.catch(() => {
console.error(`Could not load ${this._lang}.json.`);
});*/
console.log("MenuBuilder.load() end");
}
So back in onload.js you can use the promise returned from menuBuilder.load() to call translator.load() after menuBuilder.load() is done.
import MenuBuilder from "./menu-builder.js";
import Translator from "./translator.js";
var menuBuilder = new MenuBuilder();
var translator = new Translator();
menuBuilder.load().then(() => translator.load());

Implementing Dijkstra in Javascript

I am trying to get an implementation of Dijkstra's algorithm in JavaScript to run properly.
I found a walkthrough Here and do not understand the return line
return `Path is ${path} and time is ${times[endNode]}
I have collected the code from the link below to make it easier.
class Graph {
constructor() {
this.nodes = [];
this.adjacencyList = [];
}
addNode(node) {
this.nodes.push(node);
this.adjacencyList[node] = [];
}
addEdge(node1, node2, weight) {
this.adjacencyList[node1].push({node:node2, weight: weight});
this.adjacencyList[node2].push({node:node1, weight: weight});
}
findPathWithDijkstra(startNode, endNode) {
let times = [];
let backtrace = [];
let pq = new PriorityQueue();
times[startNode] = 0;
this.nodes.forEach(node => {
if (node !== startNode) {
times[node] = Infinity
}
});
pq.enqueue([startNode, 0]);
while (!pq.isEmpty()) {
let shortestStep = pq.dequeue();
let currentNode = shortestStep[0];
this.adjacencyList[currentNode].forEach(neighbor => {
let time = times[currentNode] + neighbor.weight;
if (time < times[neighbor.node]) {
times[neighbor.node] = time;
backtrace[neighbor.node] = currentNode;
pq.enqueue([neighbor.node, time]);
}
});
}
let path = [endNode];
let lastStep = endNode;
while(lastStep !== startNode) {
path.unshift(backtrace[lastStep])
lastStep = backtrace[lastStep]
}
return `Path is ${path} and time is ${times[endNode] }`
}
}
class PriorityQueue {
constructor() {
this.collection = [];
}
enqueue(element){
if (this.isEmpty()){
this.collection.push(element);
} else {
let added = false;
for (let i = 1; i <= this.collection.length; i++){
if (element[1] < this.collection[i-1][1]){
this.collection.splice(i-1, 0, element);
added = true;
break;
}
}
if (!added){
this.collection.push(element);
}
}
};
dequeue() {
let value = this.collection.shift();
return value;
};
isEmpty() {
return (this.collection.length === 0)
};
}
let testGraph01 = new Graph();
let testGraph02 = new Graph();
let testGraph03 = new Graph();
//creating graphs
testGraph01.addNode("A");
testGraph01.addNode("B");
testGraph01.addNode("C");
testGraph01.addNode("D");
testGraph01.addEdge("A","B",10);
testGraph01.addEdge("C","D",5);
testGraph01.addEdge("D","B",5);
console.log(testGraph01.findPathWithDijkstra("A","D"));
I am looking for an explanation of the templated return. How does it work in javascript i guess?

Use regular expression within constructor with Javascript

I've been having trouble trying to define a third property of a constructor. When I comment out this.partial = text.replace(cloze,'...'); it runs fine.
But when I use that line of code, the program ends mid-inquirer. I believe it has something to do with the .replace() regex.
Here's my code:
var fs = require("fs");
var action = process.argv[3];
var count = process.argv[4];
function ClozeCard(text, cloze) {
this.text = text;
this.cloze = cloze;
this.partial = text.replace(cloze,'...');
}
var inquirer = require('inquirer');
var cards = [];
var num = 0;
var start = {
createCards: function() {
if (num < count) {
inquirer.prompt([
{
name: "text",
message: "What is the Cloze-flashcard's text?"
}, {
name: "cloze",
message: "What is the Cloze-flashcard's answer?"
}
]).then(function (answers) {
var newCard = new ClozeCard(answers.text, answers.cloze);
if (answers.text.indexOf(answers.cloze) === -1) {
console.log("The answer does not appear to be in the text. Try again");
return;
} else {
cards.push(newCard);
num++;
fs.writeFile('cloze.txt', JSON.stringify(cards), function (err) {
if (err) {
return console.log(err);
}
});
start.createCards();
}
});
}
}
}
start.createCards();
module.exports = ClozeCard;

How to stop executing Javascript function containing infinite loop after some time

Suppose I have following piece of code that contains an infinite loop:
function infiniteLoop() {
while(true) {
//do something, eg.
document.getElementById("someID").innerHTML = "Blah";
}
}
If we execute this code in an online compiler, browser will crash. I want to prevent that from happening. So I tried following code following this answer:
function willNotCrash() {
myVar = setInterval(infiniteLoop, 5000);
setTimeout(function(){
clearInterval(myVar);
}, 4000);
}
This code doesn't make the browser to crash, because I am stopping the execution before infiniteLoop() gets called by clearInterval(myVar).
My question is how do I stop executing such functions if they don't response within some period of time (eg. after 5 seconds or before the browser is crashed).
For example, if we copy paste following java code in https://www.compilejava.net/
public class HelloWorld {
public static void main(String[] args) {
while(true) {
System.out.println("Blah");
}
}
}
we get a nice output saying,
Script was taking longer than 5 seconds to execute so it was killed.
Here is my current code: http://js.do/code/106546
This is a bit tricky but perfectly doable. You need to tokenize the script and then rebuild it but insert a counter increment in every loop and function call. If the counter goes above some threshold, then bomb out. I did it here: https://littleminigames.com/
You can see the source at https://bitbucket.org/cskilbeck/littleminigames/src
The interesting bits are in wrapper.js (https://bitbucket.org/cskilbeck/littleminigames/src/ac29d0d0787abe93c75b88520050a6792c04d34d/public_html/static/js/wrapper.js?at=master&fileviewer=file-view-default)
Google escodegen, estraverse and esprima
I relied heavily on this: https://github.com/CodeCosmos/codecosmos/blob/master/www/js/sandbox.js
wrapper.js, as requested:
// Don't obfuscate this file! We depend on the toString() of functions!
// this was all nicked from https://github.com/CodeCosmos/codecosmos/blob/master/www/js/sandbox.js
(function(mainApp) {
'use strict';
var esprima = window.esprima,
estraverse = window.estraverse,
escodegen = window.escodegen,
errors = [],
eng,
Syntax = estraverse.Syntax;
// This implements the jankiest possible "source map", where we keep an array
// of [generatedLine, knownSourceLine]. Seems to essentially work.
function SourceNode(line, col, _sourceMap, generated) {
this.line = line;
this.col = col;
this.generated = generated;
}
SourceNode.prototype.toStringWithSourceMap = function toStringWithSourceMap() {
var code = [];
var mapLines = {};
var map = [];
// assumes that wrapCode adds two lines
var line = 3;
var lastMapLine = null;
function walk(node) {
if (typeof(node) === "string") {
if (node) {
code.push(node);
var matches = node.match(/\n/g);
if (matches !== null) {
line += matches.length;
}
}
} else if (node instanceof SourceNode) {
if (node.line !== null) {
if (!mapLines[line]) {
map.push([line, node.line]);
mapLines[line] = node.line;
}
}
walk(node.generated);
} else {
node.forEach(walk);
}
}
walk(this);
return {
code: code.join(''),
map: map
};
};
SourceNode.prototype.toString = function toString() {
return this.toStringWithSourceMap().code;
};
// This is used by escodegen
window.sourceMap = {
SourceNode: SourceNode
};
// TODO (chs): add in all the things that need to be masked
function runWrapper($userCode, __sys) {
var clear = __sys.clear,
setpixel = __sys.setpixel,
rectangle = __sys.rectangle,
box = __sys.box,
line = __sys.line,
getpixel = __sys.getpixel,
getpixeli = __sys.getpixeli,
keypress = __sys.keypress,
keyrelease = __sys.keyrelease,
keyheld = __sys.keyheld,
reset = __sys.reset;
__sys.userFunction = __sys.catchErrors($userCode);
}
function extractCode(fn) {
var code = fn.toString();
return code.substring(code.indexOf('{') + 1, code.lastIndexOf('}'));
}
function makeOneLine(code) {
return code.replace(/(\/\/[^\n]+|\n\s|\r\n\s*)/g, '');
}
var runTemplate = makeOneLine(extractCode(runWrapper));
function wrapCode(code, template, functionName, postCode) {
// avoid interpretation of the replacement string by using a fun.
// otherwise mo' $ mo problems.
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#Specifying_a_string_as_a_parameter
return ("'use strict';" + template.replace(/\$userCode/, function() {
return 'function ' + functionName + '() {\n' + code + postCode + '\n}';
}));
}
var injectStatement = esprima.parse("if (++__sys.ctr >= __sys.maxctr) throw new Error('Script halted - infinite loop?');").body[0];
var injectElseStatement = esprima.parse("if (++__sys.ctr >= __sys.maxctr) throw new Error('Script halted - infinite loop?'); else ;").body[0];
function CallExpression(callee, args) {
this.callee = callee;
this.arguments = args;
}
CallExpression.prototype.type = Syntax.CallExpression;
function Identifier(name) {
this.name = name;
}
Identifier.prototype.type = Syntax.Identifier;
function BlockStatement(body) {
this.body = body;
}
BlockStatement.prototype.type = Syntax.BlockStatement;
function ReturnStatement(argument) {
this.argument = argument;
}
ReturnStatement.prototype.type = Syntax.ReturnStatement;
function FunctionExpression(id, params, body) {
this.id = id;
this.params = params;
this.body = body;
this.defaults = [];
this.expression = false;
this.generator = false;
this.rest = null;
}
FunctionExpression.prototype.type = Syntax.FunctionExpression;
function wrapId(node, defaultName) {
if (node.loc) {
var id = (node.id || {
name: null,
loc: null
});
var loc = id.loc || node.loc;
var name = id.name || defaultName;
return new Identifier(name + '$' + loc.start.line);
} else {
return node.id;
}
}
function instrumentAST(ast) {
var identifierStack = [];
function pushIdentifier(s) {
identifierStack[identifierStack.length - 1].push(s);
}
function popIdentifierStack() {
identifierStack.pop();
}
function pushIdentifierStack() {
identifierStack.push([]);
}
function peekLastIdentifier() {
var lastStackIdx = identifierStack.length - 1;
if (lastStackIdx >= 0) {
var stack = identifierStack[lastStackIdx];
if (stack.length) {
return stack[stack.length - 1];
}
}
return '';
}
pushIdentifierStack();
return estraverse.replace(ast, {
enter: function enterAST(node) {
switch (node.type) {
case Syntax.VariableDeclarator:
if (node.id.type === Syntax.Identifier) {
pushIdentifier(node.id.name);
}
break;
case Syntax.MemberExpression:
if (node.object.type === Syntax.Identifier) {
var id = node.object.name;
if (node.property.type === Syntax.Identifier) {
id += '__dot__' + node.property.name; // huh? why mangle these?
// console.log(id);
}
pushIdentifier(id);
} else if (node.property.type === Syntax.Identifier) {
pushIdentifier(node.property.name);
}
break;
case Syntax.FunctionDeclaration:
pushIdentifierStack();
break;
case Syntax.FunctionExpression:
pushIdentifierStack();
break;
default:
break;
}
return node;
},
leave: function leaveAST(node) {
switch (node.type) {
case Syntax.DoWhileStatement:
break;
case Syntax.ForStatement:
break;
case Syntax.FunctionDeclaration:
break;
case Syntax.FunctionExpression:
break;
case Syntax.WhileStatement:
break;
default:
return estraverse.SKIP;
}
// modify the BlockStatement in-place to inject the instruction counter
if(node.body.body === undefined) {
// they have used a non-block statement as the body of a function or loop construct
// not allowed for function declarations - should never get here
if(node.type === Syntax.FunctionDeclaration) {
errors.push({
message: "Missing {",
line: node.loc.start.line,
column: node.loc.start.column
});
}
else {
// otherwise insert the test
var newBody = angular.copy(injectElseStatement);
newBody.alternate = node.body;
node.body = newBody;
}
return estraverse.SKIP;
}
node.body.body.unshift(injectStatement);
if (node.type === Syntax.FunctionExpression) {
popIdentifierStack();
// __catchErrors(node)
node.id = wrapId(node, peekLastIdentifier());
return new CallExpression(
new Identifier("__sys.catchErrors"), [node]);
}
if (node.type === Syntax.FunctionDeclaration) {
popIdentifierStack();
// modify the BlockStatement in-place to be
// return __catchErrors(function id() { body });
var funBody = node.body;
node.body = new BlockStatement([
new ReturnStatement(
new CallExpression(
new CallExpression(
new Identifier("__sys.catchErrors"), [new FunctionExpression(
wrapId(node, peekLastIdentifier()), [],
funBody)]), []))
]);
}
return node;
}
});
}
// mainApp.sandbox('var a = 1; function update(frame) { clear(0); }').code
// give it the source code as a string
mainApp.sandbox = function(code) {
var rc = {};
this.errors = [];
try {
this.ast = instrumentAST(esprima.parse(code, { range: true, loc: true }));
this.map = escodegen.generate(this.ast, { sourceMap: true, sourceMapWithCode: true });
this.code = wrapCode(this.map.code, runTemplate, '', ';\n__sys.updateFunction = (typeof update === "function") ? update : null;');
}
catch(e) {
this.errors.push({
message: e.description,
line: e.lineNumber,
column: e.column
});
}
if(this.code) {
this.code = "eng.clientFunction = function(__sys) {" + this.code + "};";
}
};
mainApp.sandbox.prototype.searchMap = function(needle) {
// binary search
var lo = 0;
var hi = this.map.map.length;
var mid, here;
while (true) {
mid = lo + ((hi - lo) >> 1);
here = this.map.map[mid];
if (mid === lo || here[0] === needle) {
return here[1];
} else if (here[0] > needle) {
hi = mid;
} else {
lo = mid;
}
}
};
})(mainApp);
Typically all JavaScript runs in one thread, so it is impossible to run any JavaScript that could stop your loop while your loop is running. Using HTML5 web workers, you can run the infinite loop in a separate thread, and then you can terminate it:
var myWorker = new Worker( '/infinite.js ');
setTimeout( function ( ) {
myWorker.terminate( );
}, 5000 );
However your web worker won't have access to the DOM, so the contents of your infinite loop would need to be different that what you have in your question.
I found exactly what I was looking for in Bergi's comment,
Alternatively, place a if (Date.now() > dateAtStartOfExecution+5000) return; in every loop body.
So now my code looks like:
function infiniteLoop() {
dateAtStartOfExecution = Date.now();
while(true) {
//do something
document.getElementById("someID").innerHTML = "Blah";
if (Date.now() > dateAtStartOfExecution+5000) {
alert("Taking too much time. Killing.");
return;
}
}
}
If I run this code after 5 seconds I will get an alert and the execution will stop. Try this:
http://js.do/code/106565

Node Module Inheritance

I wrote the below listed module for an ExpressJS application. I now need to create a similar module with about 3 changed methods, and a few different instance variables. My plan is to create a superclass that has all the common (call it Common.js) and then require it for the two or more subclasses.
I generalized pointer to a tutorial might help me, but here are my specific questions:
the requires will be common, I suppose I put them in Common.js,
right?
I assume I should promote as many instance variables (the subclasses) into Common as possible?
The following could be a template fro the subclasses, with the Object.create coming at the top of the file
SubClass snippet:
var Common = require("./Common");
SubClass.prototype = Object.create(Common.prototype);
SubClass.prototype.subMethod = function() {....}
and also I assume that any submethod can refer to variables in the superclass, as well as new variables in the subclass, with as this.variableName,
BTW, how would I create new subClass instance variables?
Here is my original Code:
var _ = require('lodash');
var path = require('path');
var fs = require('fs');
var tools = require("../tools/tools");
var Job = require("./falconJob");
var Batch = function (ticket) {
this.counts = [];
this.maxes = [];
this.errors = [];
this.done = [];
this.jobs = 0;
this.started = Date.now();
this.ended = Date.now();
this.jobBatch = {};
this.ticket = ticket;
this.batchRoot = null;
}
Batch.prototype.setup = function (frameList, req, next) {
this.group(frameList);
this.makeRoot(req, next);
}
Batch.prototype.group = function (list) {
_.forEach(list, function (obj) {
if (this.jobBatch[obj.type] == undefined) {
this.jobBatch[obj.type] = [];
}
this.jobBatch[obj.type].push(obj);
}, this);
};
Batch.prototype.makeRoot = function (req, next) {
var config = global.app.settings.config;
this.batchRoot = path.join(config.JobsPath, this.ticket);
var self = this;
fs.mkdir(this.batchRoot, function (err) {
if (err) return next(err);
var mapInfoFile = path.join(self.batchRoot, "MapInfo.json");
var mapInfo = {
Date: (new Date()).toISOString(),
Version: global.manifestVID,
Zoom: req.body.Zoom,
CenterLat: req.body.CenterLat,
CenterLon: req.body.CenterLon
};
fs.writeFile(mapInfoFile, tools.pretty(mapInfo), function (err) {
if (err) return next(err);
return next(null);
});
});
};
Batch.prototype.spawn = function () {
_.forEach(this.jobBatch, function (files, key) {
var job = new Job(key, files, this.batchRoot, this.ticket, this);
this.begin(job);
job.exec();
}, this);
};
Batch.prototype.count = function () {
var sum = 0;
for (var key in this.counts) {
sum += this.counts[key];
}
return sum;
}
Batch.prototype.total = function () {
var sum = 0;
for (var key in this.maxes) {
sum += this.maxes[key];
};
return sum;
}
Batch.prototype.fails = function () {
var sum = 0;
for (var key in this.errors) {
sum += (this.errors[key]) ? 1: 0;
};
return sum;
}
Batch.prototype.finished = function () {
var keylist = Object.keys(this.done);
if (keylist.length == 0) return false;
for (var key in this.done) {
if (this.done[key] == false) return false;
};
if (this.jobs != 0) return false;
return true;
}
Batch.prototype.rate = function () {
var speed = (this.count() * 1000) / (this.ended - this.started); // tiles / second
return speed;
}
Batch.prototype.begin = function (job) {
var type = job.type;
this.jobs++;
this.counts[type] = 0;
this.maxes[type] = 0;
this.errors[type] = false;
this.done[type] = false;
}
Batch.prototype.end = function (job) {
type = job.type;
this.jobs--;
this.errors[type] = job.errors;
this.done[type] = true;
}
Batch.prototype.update = function (status) {
type = status.layer;
this.ended = Date.now();
this.counts[type] = status.tilesCount;
this.maxes[type] = status.tilesMax;
this.done[type] = status.done;
}
module.exports = Batch;
I am surprised, no one answered. Well I have a solution, and a few tips. First, read the Mozilla developer page about an introduction to javascript inheritance: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript
Here is how I structured my "sub-module" which I can just require in and it will pull in the super-module, and then subclass it.
var _ = require('lodash'); // require any additional modules that your sub module needs
var BatchRoot = require('./Batch'); // require the super-module with the superclass
var Job = require("./falconJob"); // another module that I need
var Batch = function (ticket) {
BatchRoot.call(this, ticket); // The superclass constructor takes "ticket" as a param
// define new subclass instance variables here, e.g. this.foobar = 33;
}
Batch.prototype = new BatchRoot(); // This does the subclassing
Batch.prototype.constructor = BatchRoot; // MDN says to do this to correct the constructor pointer because it points to Batch
// this is a new subclass function, notice that I use Job which is only defined here
Batch.prototype.spawn = function () {
_.forEach(this.jobBatch, function (files, key) {
var job = new Job(key, files, this.batchRoot, this.ticket, this);
this.begin(job);
job.exec();
}, this);
};
module.exports = Batch;

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