How to Parse a String in JavaScript?

In JavaScript, parsing a string means converting it to a different data type or format. Parsing strings is a common task in JavaScript when working with user input, external data sources, data structures, and string formatting and manipulation. While working with the user input or external sources, such as an API or a JSON file, the data is usually in string format. For performing calculations or comparisons on the specified data, developers must parse it to a specific type, like int, float, array, date, or object.

This article will demonstrate the ways to parse a string in JavaScript.

How to Parse a String in JavaScript?

For parsing a string, use the following methods:

parseInt() method
parseFloat() method
Date.parse() method
JSON.parse() method

Method 1: Parse an Integer as a String Using “parseInt()” Method

To parse a string into an integer/number type, use the “parseInt()” method. This method is utilized for parsing a string into an integer. It accepts two arguments, the “base” and the “string” to be parsed. The “base” is a number system used in the string and it is an optional parameter. If it is not specified, the method assumes base 10.

Syntax

Following syntax is used for the parseInt() method:

parseInt(str)

Or:

parseInt(str, base)

Example

Create a variable “integerString” and store a string of integer number “13856”:

const integerString = '13856';

Call the parseInt() method by passing the string as argument:

const result = parseInt(integerString);

Finally, print the result on the console using “console.log()” method:

console.log(result);

It can be seen that the string has been successfully parsed as an integer number:

Method 2: Parse a Floating-Point Number as String Using “parseFloat()” Method

For parsing a string into a floating-point number, utilize the “parseFloat()” method. It is utilized for parsing a string into a floating-point/decimal number. It accepts only one argument.

Syntax

Utilize the given syntax for the parseFloat() method:

parseFloat(str)

Example

Create a string of decimal number:

const floatString = '3.1415926';

Now, pass the string as an argument in the parseFloat() method, and print result on the console:

const result = parseFloat(floatString);

console.log(result);

Output

Method 3: Parse a Date as a String Using “Date.parse()” Method

Use the “Date.parse()” method to parse a date string in a Date object. This method parses a date string into a Unix timestamp (time in milliseconds). It also takes one argument, the date string, to be parsed.

Syntax

Follow the below-mentioned syntax for the Date.parse() method:

Date.parse(dateString)

Example

Create a variable “dateString” that stores a date and time:

const dateString = '2023-02-23T10:00:00Z';

Pass the date string in a Date.parse() method for converting it into Unix timestamp:

const result = Date.parse(dateString);

console.log(result);

The output displays time in milliseconds since Jan 1st 1990 to the date:

Method 4: Parse a JSON String Using “JSON.parse()” Method

To parse a JSON string, utilize the “JSON.parse()” method. It is utilized to parse a JSON string into an object. It can accept the JSON string as an argument to be parsed.

Syntax

The given syntax is utilized for the JSON.parse() method:

JSON.parse(JSONString)

Example

Create a JSON string:

const jsonString = '{"id":"16", "name": "Mari", "age": 28}';

Invoke the JSON.parse() method and pass a JSON string as argument:

const result = JSON.parse(jsonString);

console.log(result);

Output

That’s all about parsing a string in JavaScript.

Conclusion

To parse a string in JavaScript, use “parseInt()”, “parseFloat()” “Date.parse()” or the “JSON.parse()” methods. These methods parse the string into an integer, floating point number, Date object, and Object. This article demonstrated the methods for parsing a string in JavaScript.

How to Parse a String in JavaScript?