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  Using JavaScript to operate clipboard

Browsers allow JavaScript to read and write data on clipboard. Generally script should not modify user's clipboard to avoid impacting user expectation, but there are cases where this can indeed bring convenience to users. For example, for some code snippet, user can copy it to clipboard with one click instead of select and copy manually. There are three options for clipboard operation provided in JavaScript/browser: document.execCommand() Asynchronous Clipboard API copy and paste events This p...

   JAVASCRIPT,CLIPBOARD,NAVIGATOR.CLIPBOARD     2021-01-23 23:23:34

  What and what not to log while debugging

Log is a critical part of an application. It serves as an eye to the programmer on how the application is working while debugging. Especially for applications running on production environment, if the application encounters problem and the problem cannot be reproduced on other environments, log will be extremely useful. While log is essential, but developers have to log smartly. Because if don't put log smartly, you may not get what you want while debugging or you may get too many...

   PROGRAMMING,DEBUG,LOG,SUPPORT     2016-03-14 08:09:03

  Understanding JavaScript closure and where it can be used

Closure The official definition of closure is: an expression (usually a function) that has many variables and is bound to an environment that includes those variables. In JavaScript, closure refers to the ability of a function to access the lexical scope in which it was defined, even after the function has been executed and left that scope. This ability is due to the fact that when a function is created, it generates a closure that includes a reference to the definition environment of the curr...

   CLOSURE,JAVASCRIPT,USAGE     2023-03-05 02:17:08

  JavaScript interview questions

This post will cover the JavaScript questions I have encountered and have seen during my programming career. They will mainly focus on vanilla JavaScript though there are lots of excellent frameworks out there and many people are using them in their daily work. this keyword this keyword is an very important but easy to confuse concept in JavaScript since it is always referring to the calling object of the function. 1. What will be the output of below code snippet? function User(name) { this....

   JAVASCRIPT,ALGORITHM,THIS,CLOSURE     2019-03-09 07:05:46

  Understand JavaScript prototype

For an front end programming language like JavaScript, if we want to understand its OOP feature, we need to understand its objects, prototype chain, execution context, closure and this keyword in deep. If you have a good understanding on these concepts, you should be confident that you can handle this language well. The inheritance in JavaScript is not class inheritance like Java, but it adopts another mechanism-- prototype inheritance. The key to prototype inheritance is the prototype chain mec...

   JavaScript, prototype, __proto__     2013-02-02 02:34:09

  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

  this in JavaScript in detail

this in JavaScript is always confusing, it is one of the most frequently seen traps in JavaScript. this is not a good design in JavaScript(You can refer some other design flaws of JavaScript here), since it's lazy binding feature, it can be a global object, the current object or.... Some people even avoid using this in JavaScript. Actually if you master how this works, then you will know how to stay away from these traps. Let's take a look at what this points to in below situations. 1. In global...

   JavaScript,this,bind     2013-05-09 18:35:12

  An easy way to log client side information to server

JavaScript debug is a very troublesome thing in web application development. Because many web browsers will not notify you if there is any error in the JavaScript codes you write. They just silently fail and block the following codes execution. In order to debug JavaScript codes, we need a good log mechanism which will help us log the error information,, we often need to log errors in JavaScript codes to server for debug purpose in a production web application, What should we do? The first ...

   JavaScript log, Ajax,Image,Debug     2012-12-30 09:16:50

  Generate first N prime numbers

Recently I am taking an online course named "Startup Engineering" on coursera. There is one assignment which is to use NodeJS to write a program to generate the first 100 prime numbers. This may be very easy for many people. Here I just want to share with you the code to generate not only the first 100 prime numbers. but also any number of prime numbers. Below is the code snippet: //Helper class to generate prime numbers var PrimeProcessor=(function(){ var primeArray=[]; functio...

   Algorithm,Prime number,NodeJS,coursera,JavaScript     2013-06-29 22:08:22

  Different ways to pass query parameters in EmberJS

In EmberJS, one could pass query parameters when retrieving resources with store.query() method. But what if there is a requirement that one wants to pass query parameters when calling store.findRecord()? Or there is a requirement that one wants to pass query parameters to a relationship when calling model.get('hasManyAttribute') in a RESTful style? In this post, we will explain how these can be achieved. In the store.query() case, one could easily pass the query parameters by passing ...

   RELATIONSHIP,EMBERJS,QUERY PARAMETERS     2018-05-18 10:47:56

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