Front End Technology Articles - Page 787 of 860

In this tutorial, let us discuss the smart, self-overwriting, or lazy-getters in JavaScript. A getter binds the property of an object to a function, but the getter will not calculate the property value until we access it. The getter helps when we need to get some dynamic value without an explicit call. Users can follow the syntax below to work with the getters. Syntax { get prop() {} } { get [exp]() {} } The prop and the exp are the object's properties that bind to a function. 'prop' is a simple object property, and 'exp' is an expression. ... Read More

To execute JavaScript at the command prompt, can be achieved through various methods depending on the environment. We will be discussing three different approach which can be used to execute JavaScript at the command prompt with stepwise explanation of steps. In this article, our task is to execute JavaScript at the command prompt. Different Methods to Run JavaScript at Terminal Here is a list of methods that can be used to execute JavaScript at the command prompt which we will be discussing in this article with stepwise explaination and complete example codes. Runnning JavaScript File ... Read More

To concatenate several string, use “Array.join()” method. Here, we will concat the following strings:John Amit SachinExampleYou can try to run the following code to concat several stringsLive Demo                    var arr = ['Amit', 'John', 'Sachin'];          document.write(arr.join(', '));            

To fire a JavaScript function when the user finishes typing, try to run the following code −Example                    var timer = null;          $("#myText").keydown(function(){             clearTimeout(timer);             timer = setTimeout(doStuff, 1000)          });          function doStuff() {             alert("Write more!");          }                

Function overloading occurs when a function performs different tasks based on a number of arguments passed to it.The best practice for function overloading with parameters is to not check the types. The code runs slower when the type is checked and it should be avoided. For this, the last parameter to the methods should be an objectAlso, do not check the argument length.ExampleHere’s an example −function display(a, b, value) { } display(30, 15, {"method":"subtract"}); display(70, 90, {"test":"equals", "val":"cost"});

To view events fired on an element, follow the below steps in Google Chrome:Open Google Chrome and press F12 to open Dev Tools.Now go to Sources TabGo to Event Listener Breakpoints, on the right:Click on the events and interact with the target element.If the event will fire, then you will get a breakpoint in the debugger.

The yield keyword is used in JavaScript to pause and resume a generator function. The value of the expression is returned to the generator's caller.Here’s the syntax, where “exp” is the expression and the optional value is returned by “val”, which is passed to the generator's next() method.[val] = yield [exp];Here are the examples:function* displayRank () {    var selPlayers= [1, 2, 3, 4];    for (var a = 0; a < selPlayers.length; a++) {       yield selPlayers[i];    } }After defining a generator function, use it like the following.Here displayRank() is the generator function:var rank = displayRank(); ... Read More

The immediate function executes as soon as it is defined. To understand the role of immediate function, let’s see the difference between a function and an immediate function −Here’s immediate function −(function() {    var str = "display"; }()); function display() {    // this returns undefined    alert(str); }Here’s a function −var str = "display"; function display() {    // This returns "display"    alert(str); }Let’s see another example of immediate functions −var name = 'Amit'; (function(sName) {    alert( 'Student name = ' + sName ); }(sName))

In this tutorial, we will look at the method to preserve variables in a JavaScript closure function. What is a closure function? A closure function gives access to the scope of an outer function from an inner function. It also allows private variables. Closure variables are stored in stack and heap. When a function is created, closure is also created. Closure remembers external things used in it. Closures are the primary mechanism for data privacy. One drawback is that the variables used are not garbage collected. Overuse of closure functions will damage the system due to redundant ... Read More

In JavaScript, the functions wrapped with parenthesis are called “Immediately Invoked Function Expressions" or "Self Executing Functions.The purpose of wrapping is to namespace and control the visibility of member functions. It wraps code inside a function scope and decrease clashing with other libraries. This is what we call Immediately Invoked Function Expression (IIFE) or Self Executing Anonymous Function.Here’s the syntax −(function() {    // code })();As you can see above, the following pair of parentheses converts the code inside the parentheses into an expression −function(){...}In addition, the next pair, i.e. the second pair of parentheses continues the operation. It calls ... Read More