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SEARCH KEYWORD -- Parallel JavaScript

  Code Optimization Techniques for Graphics Processing Units

Books on parallel programming theory often talk about such weird beasts like the PRAM model, a hypothetical hardware that would provide the programmer with a number of processors that is proportional to the input size of the problem at hand. Modern general purpose computers afford only a few processing units; four is currently a reasonable number. This limitation makes the development of highly parallel applications quite difficult to the average computer user. However, the low cost and th...

   Optimazation,GUI,Graphic processing     2011-12-18 01:11:53

  Why 0.1+0.2 != 0.3

In programming languages such as JavaScript, c/c++, Java and Matlab, you will find that you will get unexpected result when doing float point calculation. For example, when calculating 0.1 + 0.1, you will not get 0.3: > 0.1 + 0.2 == 0.3 false > 0.1 + 0.2 0.30000000000000004 Don't be surprised of this result, this is the end result of IEEE 754 standard, float point number cannot be accurately represented according to IEEE 754 because: No enough memory is allocated for representing the num...

   float point,comparison,JavaScript     2014-11-19 05:32:46

  Java vs F#

Dr Cliff Click of Azul Systems, specialists in manycore JVM systems, recently published a blog post about the performance of Java compared primarily to C and C++ but also discussing C# and .NET. Three of Cliff's comments are of particular interest:Under the heading "Places where C/C++ beats Java for obvious reasons":"Value Types, such as a 'Complex' type require a full object in Java." - Dr Cliff ClickWhat Cliff forgot to mention is that .NET also provides value types and a far more compell...

   Java,F#,Performance,JVM     2012-03-07 05:07:31

  Which one has a worse reputation, JavaScript or PHP?

There has a been a lot of criticism of PHP over being a badly designed programming language. JavaScript seems quite a similar language with loose-typing and flexible array declarations/memory management, but is widely adopted by industry leaders such as Google. Google even has a JavaScript style guide. Many people think that PHP has a worse reputation than JavaScript. Carlos Ribeiro gave his analysis on a high level which doesn't touch the language syntax. Attributing JavaScript success to it be...

   JavaScript,PHP,reputation,comparison     2014-05-03 06:26:10

  Ways to check existence of JavaScript object

The design of JavaScript is not so sophisticated. It's very easy for us to make mistakes if we are not very careful when using JavaScript. For example, to check the existence of JavaScript object. Now we want to check whether a global object myObj exists or not, if it doesn't exist, we declare it. The pseudo code for this is : if(myObj not exist){ declare myObj; } You may think it's very easy to write the code. In fact, it is much more difficult than we may think. Juriy Zaytsev says there are m...

   JAVASCRIPT,OBJECT,EXISTENCE     2020-09-12 02:14:02

  Understanding an interesting JavaScript map function question

With the evolvement of JavaScript, lots of new features have been added this old but robust language.  Among them are lots of functional programming language related functions like map, filter, each etc. In this post, we will cover one function map and its interesting behavior. Before dive into the details, let first take an example, do you know the output of below function call? ['1', '7', '11'].map(parseInt) You may think that it's easy and the output would be [1, 7, 11] Can you try to ru...

   JAVASCRIPT,MAP,FUNCTIONAL PROGRAMMING     2019-06-14 08:34:46

  JavaScript: Private variables

The first thing you often hear when talking about JavaScript is often “JavaScript doesn’t have visibility modifiers, hence it doesn’t support private variables”. This is only valid for 50%, because JavaScript indeed doesn’t have visibility modifiers (public, private, friend) but it has closures and function scopes. With these tools we can make variables private. Let’s take the following function: var names = ["Kenneth", "John", "Marc", "Robert"]; var lookup =...

   JavaScript,private variable,closure     2012-04-28 11:46:34

  Roundup on Parallel Connections

A lot of blogging and follow-up discussion ensued with the announcement that IE8 supports six connections per host. The blogs I saw: IE8: The Performance Implications IE8 speeds things up IE8: 6 Connections Per Host IE 8 and Performance Testing IE8.s Connection Parallelism IE 8 Connection Parallelism Issues It’s likely that Firefox 3 will support 6 connections per server in an upcoming beta release, which means more discussion is expected. I wanted to pull all the facts into one place an...

   Browser,Concurrent connection,Persistent     2011-09-05 01:51:44

  Name resolution order in JavaScript

To understand what value a variable has in JavaScript, we need to understand some concepts such as scope and name resolution order. JavaScript has two scopes; one is program level and the other one is function level. Unlike in C,C++ or Java, JavaScript has no block level scope. So a variable defined in a if block will still be available outside. For example, the below example: var foo = 1; function bar() { if (true) { var foo = 10; } alert(foo); } bar(); The alert will display 10 since the ...

   JavaScript,Scope,Name resolution     2013-07-10 01:29:28

  Update parent window after closing the window opened by window.open()

Imagine we have a webpage which has a text field to let user enter a date. Usually, we may create a calendar window to ask the user to pick one date from the calendar window, when the date is picked, the calendar window will close and the date picked will be put into the text field. This way involves the window.open() method in JavaScript, and we may think how the opened window knows its parent window and then updates the parent window. I give a simple demo on this.We have two pages, on is the p...

   window.open, JavaScript,update, return value     2012-06-23 01:36:32

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