How to Convert a String to a Number in JavaScript
Published: 2023-11-29 01:34:52

When it comes to converting string to number in JavaScript, there are many ways by which you can achieve that.
In this article, we are going to explore; five(5) ways by which you can convert a string to a number in JavaScript.

##How to convert a string to a number using the plus (+) operator.##

One of the ways by which you can convert a string into a number in JavaScript is by using the **unary plus (+) operator** or simply by using the plus symbol.

Let's see an example of how this looks like in code.

In this example, we are using the **let** keyword to declare a variable called **stringToNumber** with a value of "25" which is a string.

Let's see how to convert the string "25" to a number,

```JavaScript
let stringToNumber = "25";
console.log(+stringToNumber);// 25
console.log(typeof stringToNumber) // string
``` 

**Assuming** you have a **variable** called **word** set to a value of **"I am a word"** which is a string as below;

```JavaScript
let word = "I am a word"
console.log(word) // I am a word
console.log(typeof word) // string
```

**Try** to convert the **word** into a number, using the **plus** *(+)* **operator** as below;

```JavaScript
let word = "I am a word"
console.log(+word)// NaN (Not a Number)
console.log(typeof word) // string
```

##Converting string to a number using the number() method or function.##
Let's see in code how this works:

```JavaScript
let stringToNumber = "25";
```

From our earlier example, we know
```JavaScript
console.log(typeof stringToNumber); // string
```

**Now, when** we do 
```JavaScript
console.log(Number(stringToNumber)); // 25
```

**Keep in mind** the **Number()** is case sensitive so ***Number()*** is not the same as **number()**.

**Let's see what will be printed to the console using the **Number()** method if it is a word using our **let word = "I am a word"** variable declaration as above.

```JavaScript
let word = "I am a word";
console.log(Number(word)); // NaN just as in the case of the plus(+) operator above.
``` 
**Try it yourself.**

##Converting a string to a number using the parseInt() function method.##
Another way of converting a string to a number is by using the **parseInt() function**.
Check it out in the code below using our stringToNumber example:

```JavaScript
let stringToNumber = "25";
console.log(parseInt(stringToNumber); // 25.
```
**parseInt()** method using our **word** example:

```JavaScript
let word = "I am a word"
console.log(parseInt(word))// NaN.
```
Note, however, that the parseInt() function can take in two arguments; the string you are passing in and an **optional radix**.
A **radix** is a number between 2 and 36 which represents the base in a numeral system. For example, a radix of 2 would represent the binary system, while a radix of 10 represents the decimal system.

##Converting a string to a number using the Math.floor() function##

Using the **let stringToNumber = "25",** let's see the output of the Math.floor() method in code;

```JavaScript
let stringToNumber = "25";
console.log(Math.floor(stringToNumber)); // number
```

Math.floor() will return NaN using the let word = "I am a word" variable declaration.
Check it below;

```JavaScript
let word = "I am a word"
console.log(Math.floor(word))// NaN
```

##Converting a string to a number using the Math.ceil() function##

The Math.ceil function can also be used to convert a string to a number by rounding the number to the nearest integer if the number is a decimal. 

**Let's see in code;**

```JavaScript
let stringToNumber = "25.7"
console.log(Math.ceil(stringToNumber)) // 26 thus rounding the number to the nearest integer.
```
**Another example to show something**
```JavaScript
let stringToNumber = "25.1"
console.log(Math.ceil(stringToNumber)) // 26
```
**Math.ceil()** will return NaN with our **word* variable declaration.

```JavaScript
let word = "I am a word"
console.log(Math.ceil(word))// NaN
```
##Thank you for reading.##
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To read about other methods of converting a string to a number in JavaScript, please read from the [freeCodeCamp website](https://www.freecodecamp.org/news/how-to-convert-a-string-to-a-number-in-javascript/).