Javascript type conversion with examples

In programming, type conversion is the process of converting data of one type to another. For example: converting Number data to String.

There are two types of type conversion in JavaScript.

1) Implicit Conversion - automatic type conversion

2) Explicit Conversion - manual type conversion

1) JavaScript Implicit Conversion

In certain situations, JavaScript automatically converts one data type to another (to the right type). This is known as implicit conversion.

Example 1: Implicit Conversion to String

        
let result;

result = '5' + 2; 
console.log(result)   // output : "52"

result = '5' + true; 
console.log(result);  // output : "5true"

result = '5' + undefined; 
console.log(result);  // output :"5undefined"

result = '5' + null; 
console.log(result);  // output : "5null"        
    

Example 2: Implicit Conversion to Number

        
let result;
result = '5' - '2'; 
console.log(result);  // output : 3

result = '5' - 2;
console.log(result);  // output : 3

result = '5' * 2;
console.log(result);  // output : 10

result = '5' / 2;
console.log(result);  // output : 2.5        
    

Example 3: Implicit Boolean Conversion to Number

        
// if boolean is used, true is 1, false is 0

let result;
result = '5' - true;
console.log(result);  //output : 4

result = 5 + true;
console.log(result);  // output : 6

result = 5 + false;
console.log(result);  //output : 5        
    

Example 4: undefined used with number, boolean or null

        
let result;

result = 5 + undefined;
console.log(result);  	 // output : NaN

result = 5 - undefined;
console.log(result); 	 // output : NaN

result = true + undefined;
console.log(result);  	 // output : NaN

result = null + undefined;
console.log(result);  	 // output : NaN
        
    

JavaScript Explicit Conversion

You can also convert one data type to another as per your needs. The type conversion that you do manually is known as explicit type conversion.

1. Convert to Number Explicitly

        
let result;
// string to number
result = Number('123');
console.log(result);	 // output : 123

result = Number('624e-1')  
console.log(result);	 // output : 62.4

// boolean to number
result = Number(true);
console.log(result); 	 // output : 1

result = Number(false);
console.log(result); 	 // output : 0        
    

  2. Convert to String Explicitly

        
//number to string
let result;
result = String(123);
console.log(result);  	 // output : "123"

result = String(3 + 5);
console.log(result); 	 //  output : "8"

//other data types to string
result = String(null);
console.log(result); 	 // output : "null"

result = String(undefined);
console.log(result); 	 //  output : "undefined"
        
    
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Ankit Patel

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