# fastest way to change a string to a number javascript with code examples

JavaScript is one of the most popular programming languages widely used in the world of web development. It is a dynamically typed language and can work with a variety of data types. In JavaScript, we often come across the need to convert a string into a number. Sometimes we need this conversion to perform mathematical operations or to compare numbers with each other. In this article, we will discuss the fastest way to change a string into a number in JavaScript with code examples.

JavaScript provides several built-in methods and functions for converting strings into numbers. Here are a few of them:

1. parseInt()

The parseInt() method is a built-in function that converts a string into an integer. It takes two arguments – the first argument is the string that needs to be converted and the second argument is the radix (base) in which the string should be converted.

Here's an example:

```let str = "10";
let num = parseInt(str);
console.log(num); //Output: 10
```

In this example, we passed the string "10" as an argument to the parseInt() method, which returned the number 10 as output. We did not provide a second argument to the parseInt() method, so it assumed that the base is 10 by default.

We can also provide the radix (base) as the second argument to the parseInt() method. For example:

```let str = "1010";
let bin = parseInt(str, 2);
console.log(bin); //Output: 10
```

In this example, we passed the string "1010" as an argument to the parseInt() method, and the radix 2 as the second argument. Therefore, it converted the binary number "1010" into decimal "10".

1. parseFloat()

The parseFloat() method is a built-in function that converts a string into a floating-point number. It works similarly to the parseInt() method, but it converts a float instead of an integer.

Here's an example:

```let str = "3.14159";
let num = parseFloat(str);
console.log(num); //Output: 3.14159
```

In this example, we passed the string "3.14159" as an argument to the parseFloat() method, which returned the number 3.14159 as output.

1. Number()

The Number() method is a built-in function that converts a string into a number. It can convert both integers and floats.

Here's an example:

```let str1 = "10";
let str2 = "3.14159";
let num1 = Number(str1);
let num2 = Number(str2);
console.log(num1); //Output: 10
console.log(num2); //Output: 3.14159
```

In this example, we passed two strings as arguments to the Number() method, which returned the respective numbers as output.

1. Unary Plus Operator

The Unary Plus Operator (+) is not a method but an operator that converts a string into a number. It works only with numeric strings, which means strings that include only numbers.

Here's an example:

```let str = "10";
let num = +str;
console.log(num); //Output: 10
```

In this example, we used the unary plus operator (+) before the string "10", which converted the string into a number.

All of the above methods are fast and efficient for converting strings into numbers in JavaScript. However, for large-scale applications, the parse method is the most efficient.

In conclusion, we can say that JavaScript provides many built-in methods for converting strings into numbers. Depending on the use case, you can choose the appropriate method that best fits your requirements. Always remember to check the output of your conversion thoroughly to ensure its accuracy.

let's discuss some more about the previous topics we covered.

1. parseInt()

The parseInt() function is widely used for converting a string to an integer in JavaScript. It is a very convenient method when we want to extract a number from a string and use it for making calculations. However, it is important to keep in mind that if the string contains any non-numeric characters, parseInt() will stop converting and ignore the remaining characters in the string.

Here's an example:

```let str = "1234hi5";
let num = parseInt(str);
console.log(num); //Output: 1234
```

In this example, the string "1234hi5" contains non-numeric characters after the numeric value "1234". Therefore, parseInt() ignores the "hi5" and returns only the numeric value "1234" as output.

Another important thing to note is that if the radix (base) is not specified as a second argument of the parseInt() method, it will use the default base 10 for conversion.

Here's an example:

```let str = "10";
let num = parseInt(str);
console.log(num); //Output: 10
```

In this example, we did not specify any radix as the second argument of parseInt() method. Therefore, it used the default base 10 for conversion and returned the number "10" as output.

1. parseFloat()

The parseFloat() function can be used for converting a string to a floating-point number in JavaScript. It works similarly to parseInt() function, but it converts the string into a float instead of an integer.

Here's an example:

```let str = "3.14";
let num = parseFloat(str);
console.log(num); //Output: 3.14
```

In this example, the string "3.14" is converted to a floating-point number "3.14" using the parseFloat() function.

It is important to note that parseFloat() will work correctly only if the string contains a floating-point number. If the string contains any non-numeric characters, parseFloat() will return NaN (Not a Number) as output.

Here's an example:

```let str = "3.14abc";
let num = parseFloat(str);
console.log(num); //Output: 3.14
```

In this example, the string "3.14abc" contains non-numeric characters after the floating-point number "3.14". Therefore, parseFloat() ignores the "abc" and returns only the floating-point number "3.14" as output.

1. Number()

The Number() function can also be used for converting a string to a number in JavaScript. It can be used for both integers and floating-point numbers.

Here's an example:

```let str1 = "10";
let str2 = "3.14";
let num1 = Number(str1);
let num2 = Number(str2);
console.log(num1); //Output: 10
console.log(num2); //Output: 3.14
```

In this example, we used the Number() function to convert two strings into numbers. The first string "10" is an integer, and the second string "3.14" is a floating-point number. Therefore, Number() converted both strings into the respective numbers as output.

It is important to note that the Number() function is less strict than parseInt() and parseFloat() functions. If the string contains non-numeric characters, instead of returning NaN, it will return a value of 0.

Here's an example:

```let str = "3.14abc";
let num = Number(str);
console.log(num); //Output: 0
```

In this example, the string "3.14abc" contains non-numeric characters after the floating-point number "3.14". Therefore, Number() will return a value of 0 as output.

In conclusion, all the methods discussed in this article are efficient and fast for converting a string to a number in JavaScript. However, it is important to be mindful of the presence of non-numeric characters in the string and choose the method accordingly.

## Popular questions

1. What is the fastest way to convert a string to a number in JavaScript?

In JavaScript, there are several built-in methods available for converting a string to a number. Among them, the unary plus operator and parseInt() method are considered the fastest ways for converting a string to a number.

1. How does the unary plus operator convert a string into a number in JavaScript?

The unary plus operator is an efficient way to convert a string to a number in JavaScript. It works by adding a unary plus symbol (+) before the string, which converts the string into a number.

For example, `let str = "10"; let num = +str; console.log(num);` will output "10".

1. What is the difference between parseFloat() and parseInt() methods?

Both parseFloat() and parseInt() methods are used for converting a string into a number in JavaScript. However, the main difference between them is that parseFloat() converts a string into a floating-point number whereas parseInt() converts a string into an integer.

1. Can Number() function convert a string into both integers and floating-point numbers?

Yes, the Number() function can be used for converting a string into both integers and floating-point numbers in JavaScript.

For example, `let num1 = Number("10"); let num2 = Number("3.14"); console.log(num1); console.log(num2);` will output "10" and "3.14" respectively.

1. What happens when a non-numeric character is present in the string?

If a non-numeric character is present in the string, the output would depend on the method being used for conversion. parseInt() and parseFloat() methods will stop converting and ignore the remaining characters in the string. On the other hand, the Number() function will return a value of 0 if the string contains non-numeric characters.

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##### Ahmed Galal
As a senior DevOps Engineer, I possess extensive experience in cloud-native technologies. With my knowledge of the latest DevOps tools and technologies, I can assist your organization in growing and thriving. I am passionate about learning about modern technologies on a daily basis. My area of expertise includes, but is not limited to, Linux, Solaris, and Windows Servers, as well as Docker, K8s (AKS), Jenkins, Azure DevOps, AWS, Azure, Git, GitHub, Terraform, Ansible, Prometheus, Grafana, and Bash.
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