What is the parseInt() Method in JavaScript?

Last updated on October 2, 2022 by Ayaz Ali Shah

Before learning parseInt, it is necessary to understand the data types in javascript. In javascript, we have data types like numbers, strings, objects, etc. The parseInt function works with two data types number and string.

Number: Numbers are 0 to 10 or uncountable numeric digits. In this data type, we are not allowed to add commas, dots, and any other special character. Numbers can be calculated with arithmetic operators.

String: string can be a text and number but cannot calculate.

In this article, we will learn about the parseInt() javascript function. The parseInt() is a function that converts a string to an integer. An integer is a numeric digit without a comma or dot. You can calculate the numbers but if a number’s type is a string then it cannot be calculated.

The parseInt() method accepts two parameters (string, radix), if a number has a string type then we can use the parseInt function to convert it into an integer.

var numberInString = '123';
console.log(numberInString + 2);
// Output 1232

In the above example, we have a number value with a string type that cannot be calculated. We tried to sum both values through an arithmetic operator but we got concatenated value in the result. It is because numberInString variable has a numeric value with string type.

Now let’s see the below example,

var numberInString = '123';
console.log(parseInt(numberInString) + 2);
// Output 125

In the above, we used the parseInt() method to convert the numberInString value into an integer. After converting it into an integer we summed it through an arithmetic operator which returns the expected result.

If we pass an alphanumeric value as an argument in the parseInt() method then it would return NAN. In the below example, you can see variable ticket has a string that contains two words first Number and 50. That’s why the parseInt() method returns NaN.

const ticket = 'Number 50';
// returns NaN


In this article, we learned how to use the parseInt() method to convert string values into integers. If you would like to learn more then check out the JavaScript page.

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