Technology and General Blog

In programming languages, loops are employed to operate a block of code frequently until eventually a particular situation is content. All key programming languages, which include JavaScript, consist of the principle of loops.

JavaScript is a textual content-based mostly scripting language typically utilised to insert dynamic and interactive elements to static web sites to make them visually desirable.

Loops have different syntax in each and every programming language, but the simple thought (logic) continues to be the identical.

Most programming languages have far more than one particular form of loop. The famed are for and though loop. This guideline will only understand about the loop and where by it ought to be employed in its place of other loops (favored over other loops).

Loops can be interchanged with each individual other in most situations, but loops should really be employed when you have to operate a determinate selection of iterations (when you previously know the variety of periods the loop will operate).

For Loop Syntax:

First, we should talk about the syntax for loop works by using in JavaScript:

for (initialization condition **variable benefit modifier statement**)

Code to be executed

In for loop:

  • First, initialize/established a variable(initialization runs in advance of the execution of the entire body) i.e. permit i=
  • Secondly, outline the ailment for the loop(this assertion operates before the execution and decides regardless of whether the loop will operate or not), i.e., i <= 10
  • Lastly, The third and the last statement runs after the body of the loop is executed. It modifies the value of the variable for the next iteration, i.e i++ or i–

Note: We will use the browser console to demonstrate examples performed in this post. To open up the browser console:

  • Use the F12 key in Chrome and other chromium-based browsers.
  • Use CTRL + SHIFT + K keyboard shortcut keys for Mozilla.
  • Use Option + ⌘ + C keyboard shortcut keys in Safari (if developer menu does not appear, then open Preferences by pressing ⌘ +, and in Advanced tab check “Show Develop menu in menu bar”).

How to use for loop?

We will take a programmer as an example who has to output a sequence of numbers from one to twenty using JavaScript. They will have to write twenty lines of code to output this sequence. This way of writing code is very inefficient.

We can efficiently write such repetitive tasks using loops. As mentioned above, the number of lines in the program can be reduced from twenty to four using a for a loop.

for (let number = 1 number <= 20 number++)


Now let’s discuss how a for loop actually works. The first statement, i.e., initialization, runs before the statements present inside the body of the loop and sets a variable. The second statement also runs before the execution of the block of code. It defined the condition for the loop. This statement decides whether the loop will run for the next iteration or stop at the current iteration. The third and the last statement runs after the statements inside the loop are executed. It is incrementing the value present inside the variable.

We can also decrement the value of a variable in a loop. Now we will output the sequence from twenty to one in descending order:

for (let number = 20 number > range)


What is for/in the loop?

The for/in loops are made use of to loop by the qualities present inside of an item. It will come in useful when you have to operate a loop by means of an item but do not know the amount of houses existing in the object.


for (varin item)


  • Right here var is utilised to retail store a distinctive house identify in just about every iteration.
  • The loop operates as a result of the houses of the specified object.
var worker = fname:“John”, lname:“Doe”, age:20, Id:001, Department: “Wellbeing & Security”

for (let prop in employee)


What is for/of the loop?

The for/of loops are used to loop by means of the values of an array.

var names= [‘John Smith’, ‘John Doe’, ‘Jane Doe’]

for (allow benefit of names)


for/of loops can also be utilised to operate by means of the values of a string.


Loops are used to produce concise and productive code. They do away with repetitiveness from code. They are a essential portion of any significant programming language.

As stated higher than, for loops, choose three arguments. The 1st argument/parameter is the initializer that sets the variable. The next argument is the affliction The loop will continue running right up until that affliction results in being false. The 3rd and the past argument is made use of to modify the variable which was set in the initial argument. All of these a few arguments are optional. These a few arguments should really always be specified inspite of them being optional. Failing to give arguments to a loop can produce an infinite loop that can trigger a crash program. The for loops are generally applied when the coder is aware the variety of times the loop will run.

In this how to guideline, we acquired to use for loops using JavaScript syntax. We have also uncovered about for/in and /of loops.

Leave a Reply

Your email address will not be published. Required fields are marked *