Use dynamic variable names inside JavaScript loop.

Javascript — dynamically generated variable names!

Sometimes i feel like — put my hands up in the air .. no, sorry this post was not about songs and lyrics and putting your limbs airborne .. it’s about my old issue that I thought I can’t pull with javascript — but I was wrong. And that is, to generate some sort of ‘loop-able’ variable names — naming,, naming.. 🙁 Sort of, to be able to make variables in series, like: var1, var2, var3 . simply by looping:

// some random arr var arr = [ 2, 1, 4, 'cat', true, false, null ] ; // loop and generate dynamic variable names for( var i = 0; i  arr.length; i++) var var+i = i * i; // >> this will surely fail, can't do that in JS > 

But that is not doable in javascript.. and that got me pretty hard .. because my brain think in way that should be doable . So today I found out that solution to that problem was instead of variables, to think of array members .. we can easily change keys in array, and as in this simple example below I’ll be able to iterate over loop and add any key as variable name to it:

// some random arr var arr = [ 2, 1, 4, 'cat', false ] ; // foo array is "holder" of dynamic variables var foo = [] ; // loop and generate dynamic variable names for( var i = 0; i  arr.length; i++) foo[ "slider" + arr[ i ] ] = [ i ] > console.log( foo ); // [slider2: 2, slider1: 3, slider4: 0, slidercat: 1, sliderfalse: 6] 

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How to Use Dynamic Variable Names in JavaScript?

In JavaScript, dynamic variable names are rarely utilized to update the names of variables in programs. The dynamic variable is not assigned by providing any value. Its value is changed/updated dynamically. This strategy has its own importance in advanced or complex programming to implement real-world problems.

Like the PHP language, JavaScript faces difficulty implementing variable names dynamically. However, the same output can be achieved through multiple strategies. Now, users do not need to hard code the variable name for dynamic purposes. Two auto-generated strategies are introduced, which dynamically modify the variable names during the execution of a program known as eval() and window object.

In this post, a demonstrated overview is provided of how to use dynamic variable names in JavaScript. The outcomes of this post are listed below:

Method 1: Using the eval() Method for Dynamic Variable Names

The dynamic variable names mean that the names of variables are modified randomly or are user-defined. The eval() method is specifically utilized to evaluate the JavaScript code in a string format. The method takes a string as input in the format of a JavaScript expression. After that, the method evaluates the expression in JavaScript. The developers utilize the for loop to dynamically update the multiple variable names with the eval() method.

An example is provided to implement the eval() method for dynamic variable names. The code is as below.

console. log ( ‘An example to implement eval() method’ ) ;

var a = ‘Welcome to JavaScript’ ;

The description of the code is as follows:

In this code, the eval() method is utilized to dynamically update the variable name from a to b. The console.log() method is used to get the specific values.

The output returns the above executable code and displays the dynamic variable names with the eval() method in JavaScript.

Method 2: Using the Window Object for Dynamic Variable Names

In JavaScript, a window object is basically a global object. The object can access any method or global variable in JavaScript code. Moreover, the user can make the dynamic variable with the help of a formatted string. The window object is employed to access global variables or functions in JavaScript code. This strategy is important if the user creates a global variable.

The code is written below to implement the window object for dynamic variable names in JavaScript.

console. log ( ‘Another example to implement window object method’ ) ;

console. log ( «Welcome to JavaScript» ) ;

console. log ( «Welcome to JavaScript World» ) ;

The description of the above code is listed here.

• The variable n1 is initialized with 1.
• After that, assign the value of n1 to x1 using the dot operator, such as a window.n1 object.
• Similarly, access the value of n2 to x2 using the square bracket [ ].
• Finally, execute the code to display the dynamic variable names in JavaScript.

The output shows the dynamic variable names x1 and x2 are utilized by employing the window object in JavaScript.

Conclusion

Two strategies, the eval() method and window object, are employed to use dynamic variable names in JavaScript. The eval() method takes a string of JavaScript expressions as input and evaluates them. The window object is utilized to access any method and global variables for dynamically updating the variable names. You have learned here to use dynamic variable names using JavaScript. For further understanding, we have provided a set of examples to implement the problem by following eval() and the window object strategy in JavaScript.

About the author

Syed Minhal Abbas

I hold a master’s degree in computer science and work as an academic researcher. I am eager to read about new technologies and share them with the rest of the world.

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Create and use dynamic variable names in JavaScript

Dynamic variables are those types of variables that don’t have any specific name in the code through hard coded. A dynamic variable name is auto-generated while running the program. It is possible to create a dynamic variable in JavaScript and then using it for a specific task.

In this tutorial, I am going to show you how to create a dynamic variable and then how to use it in JavaScript. So let’s continue following this tutorial.

Here in this article, we will show you the two methods that can be followed to create dynamic variables. So let’s see…

Method 1: using eval() function

The eval() function evaluates any JavaScript code in the form of a string. For example:

The above example will create a variable myNum and store value 88 in it.

Now below is the example of creating an adynamic variable using the eval() function:

for (var i = 0; i for loop executes the code inside it.
Method 2: using the Window object
In the browser, the window object is the global object. Using it also we can create a dynamic variable which will run on our browser. Without wasting any time, let’s see below is the example of generating dynamic variables using the JavaScript window object:
for(i = 1; i < 5; i++) < window['var_'+i] = + i; >console.log(var_1); console.log(var_2); console.log(var_3); console.log(var_4); console.log(var_5);
 
Now if you run the above code, then it will be proven that our code is successfully able to generate variable names dynamically.
 
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How do I create dynamic variable names inside a JavaScript loop?
 
In this tutorial, we will use the dynamic variable names inside the JavaScript loop. The dynamic variables name means it is not hardcoded already, and we can create it according to our needs from some other string values.
 
In JavaScript, there are not many applications of the dynamic variable, but it is needed while developing the real-time application. For example, while developing any application, the programmer wants to store any user-related entity to the variable with the same name as the username. In this scenario, programmers need to create dynamic variables inside JavaScript.
 
Users can also refer to the below examples to understand the dynamic variable's requirements. Suppose a programmer wants to store some values in the local storage, and they need unique names for every key. To create the unique key, they must use dynamic variables.
 
So, there are lots of applications of the dynamic variables. Below, we have implemented the different methods to create the dynamic variables.
 
Use an Array of Variables
 
The simplest JavaScript method to create the dynamic variables is to create an array. In JavaScript, we can define the dynamic array without defining its length and use it as Map. We can map the value with the key using an array and also access the value using a key.
 
Syntax
 
Users can follow the below syntax to create the dynamic array to store dynamic variables.
 
Example
 
In the example below, we have used the dynamic array to create the variables. We have stored the square of some even numbers by considering the number as the key and the square as the value.
 
    
Use dynamic variable names inside JavaScript loop.
 
Accessing the different square values from the array.
 let value = document.getElementById("value"); let dynamic = []; // storing the squre of even number in dynamic array for (let user_id = 0; user_id < 30; user_id += 2) < dynamic[user_id] = user_id * user_id; >value.innerHTML += "square of 4 is - " + dynamic[4] + ". 
"; value.innerHTML += "square of 4 is - " + dynamic[10] + ". 
"; value.innerHTML += "square of 4 is - " + dynamic[22] + ". 
"; 
 
Use the eval() Method
 
In JavaScript, the eval() method evaluates the expression we pass as a parameter. It takes the string of the JavaScript expression and evaluates it. In our case, we will pass the formatted string to create the dynamic variable.
 
Syntax
 
eval (JavaScript_expression);
 
Parameters
 
 
JavaScript_expression − It is a JavaScript expression in the string format. Users can also pass the formatted string.
 
 
Example
 
The below example demonstrates the use of the eval() method to create the dynamic variables. We have the array of user names, and we are creating the variables according to user names and accessing the values of it, and rendering them on the screen.
 
  
Use dynamic variable names inside JavaScript loop.
 
Creating dynamic variable according to username and storing value into it:
 let value = document.getElementById("value"); let user = ["user1", "user2", "user3", "user4", "user5"]; // creating variable same as username and storing userid into that. for (let user_id = 0; user_id value.innerHTML += "value for user1 is - " + user1 + ". 
"; value.innerHTML += "Value for user5 is - " + user5 + ". 
";  
 
Using the Window Object
 
The window object is defined by default in every browser. Users can access every global variable in the code using the window object. Furthermore, programmers can create the dynamic variable using the formatted string and window object.
 
Syntax
 
Users can follow the below syntax to store variables in the window object.
 
for ( let i = 0; i < 10; i++ ) < window[ ‘user’ + i ] = value; >let val = user0; // to access the dynamic variables
 
Example
 
We have used a window object to store the global variables in this example. We are accessing the values from the user array and making them global variables using the window object.
 
    
Use dynamic variable names inside JavaScript loop.
 
Creating dynamic variable according to user array and storing to window object.
 let value = document.getElementById("value"); let user = ["user1", "user2", "user3", "user4", "user5"]; // creating variable same as username and storing into window object. for (let user_id = 0; user_id value.innerHTML += "value for user 1 is - " + user1 + ". 
"; value.innerHTML += "Value for user 5 is - " + user5 + ". 
";  
 
Conclusion
 
This tutorial has three different approaches to creating the dynamic variables inside the loop. The first approach is the easiest one and most used. Moreover, if the user wants to make global variables, they can use the third approach using the window object.
 
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JavaScript Dynamic Variable Name
 
 
 
Use eval() to Create Dynamic Variable Name in JavaScript
 
Use window Object to Create Dynamic Variable Name in JavaScript
 
 
This tutorial is about JavaScript dynamic variable name, where we’ll learn about its definition, creation and use in JavaScript. We don’t use hard code dynamic variables but are auto-generated during the program’s execution.
 
We can use the eval() function and the window object to learn JavaScript dynamic variable names.
 
The eval() is a global object’s function property that executes JavaScript code represented as a string.
 
The eval() evaluates expression if its argument is an expression and runs statements if its argument’s one or multiple JavaScript statements.
 
eval() can also execute malicious code in the application without your permission. In this way, the application’s scope is also visible to third parties, leading to possible attacks. So, it is good to never use eval except for learning purposes.
 
We can also create dynamic variables in JavaScript using the window object. It is a global object that runs on our browser.
 
Let’s understand both ways via example code.
 
Use eval() to Create Dynamic Variable Name in JavaScript
 
var j = 'item'; var i = 0; for(i = 1; i  5; i++)   eval('var ' + j + i + '= ' + i + ';'); > console.log("Item1 = " + item1); console.log("Item2 = " + item2); console.log("Item3 = " + item3); console.log("Item4 = " + item4); 
 
"Item1 = 1" "Item2 = 2" "Item3 = 3" "Item4 = 4" 
 
In the above code, we create dynamic variable names using the eval() , which executes a statement to declare the item and assign the value of i .
 
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