JavaScript Type Conversion

In programming, type conversion is the process of converting data of one type to another. For example, converting string data to number.

There are two types of type conversion in JavaScript:

• Implicit Conversion - Automatic type conversion.
• Explicit Conversion - Manual type conversion.

JavaScript Implicit Conversion

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

// numeric string used with + gives string type
let result;

// convert number to string
result = "3" + 2; 
console.log(result, "-", typeof(result));

result = "3" + true; 
console.log(result, "-", typeof(result));

result = "3" + null; 
console.log(result, "-", typeof(result));

Output

32 - string
3true - string
3null - string

In this example, we performed implicit type conversion using the + operator with a string and another data type.

Here,

• "3" + 2 - Converts the number 2 to string and joins it to "3", resulting in the string "32".
• "3" + true - Converts the boolean true to string and joins it to "3", resulting in the string "3true".
• "3" + null - Converts null to string and joins it to "3", resulting in the string "3null".

Note: The typeof operator gives the data type of the variable.

JavaScript Explicit Conversion

In explicit type conversion, you manually convert one type of data into another using built-in functions. For example,

let result;

// convert string to number
result = Number("5");
console.log(result, "-", typeof(result));

// convert boolean to string
result = String(true);
console.log(result, "-", typeof(result));

// convert number to boolean
result = Boolean(0);
console.log(result, "-", typeof(result));

Output

5 - number
true - string
false - boolean

Here,

• Number("5") changes the string "5" into the number 5.
• String(true) turns the boolean true into the string "true".
• Boolean(0) converts the number 0 to the boolean false because 0 is considered a falsy value in JavaScript.

// numeric string used with - , / , *
// results in number type

let result;

result = "4" - "2"; 
console.log(result, "-", typeof(result));

result = "4" - 2;
console.log(result, "-", typeof(result));

result = "4" * 2;
console.log(result, "-", typeof(result));

result = "4" / 2;
console.log(result, "-", typeof(result));

2 - number
2 - number
8 - number
2 - number

Also Read:

• JavaScript Dates to Numbers
• JavaScript Dates to Strings