TypeScript is a powerful, typed superset of JavaScript that compiles to plain JavaScript. One of the common tasks in programming is converting strings to numbers. In TypeScript, there are several ways to convert a string to a number.

Method 1: Using parseInt() and parseFloat()

The parseInt() and parseFloat() functions are built-in JavaScript functions that can be used to convert a string to an integer or a floating-point number, respectively.

```
let num1 = parseInt("123");
console.log(num1); // 123
let num2 = parseFloat("3.14");
console.log(num2); // 3.14
```

Method 2: Using + operator

Another way to convert a string to a number in TypeScript is by using the + operator. This method is useful when the string contains only numeric characters.

```
let num1 = +"123";
console.log(num1); // 123
let num2 = +"3.14";
console.log(num2); // 3.14
```

Method 3: Using Number()

The Number() function can also be used to convert a string to a number in TypeScript.

```
let num1 = Number("123");
console.log(num1); // 123
let num2 = Number("3.14");
console.log(num2); // 3.14
```

Method 4: Using ~~ (double tilde) operator~~) operator is a fast way to convert a string to a number in TypeScript.

The double tilde (

```
let num1 = ~~"123";
console.log(num1); // 123
let num2 = ~~"3.14";
console.log(num2); // 3
```

Method 5: Using Number.parseInt() and Number.parseFloat()

TypeScript also provides Number.parseInt() and Number.parseFloat() functions to convert a string to a number. These functions work in the same way as parseInt() and parseFloat() functions.

```
let num1 = Number.parseInt("123");
console.log(num1); // 123
let num2 = Number.parseFloat("3.14");
console.log(num2); // 3.14
```

It's important to note that if the string is not a valid number, parseInt() and parseFloat() will return NaN, while Number() and the + operator will return NaN if the string cannot be parsed to a number. Additionally, ~~ operator will return 0 for invalid string.

In conclusion, TypeScript provides several ways to convert a string to a number, including parseInt(), parseFloat(), + operator, Number() function, ~~ operator and Number.parseInt() and Number.parseFloat() functions. Each method has its own set of advantages and disadvantages, so it's important to choose the right method depending on the specific use case.

Method 6: Using the `Number.isNaN()`

function

In some cases, you may need to check if a value is a valid number before converting it. The `Number.isNaN()`

function can be used to check if a value is not a number. Here's an example:

```
let str = "not a number";
if (!Number.isNaN(+str)) {
let num = +str;
console.log(num);
} else {
console.log("Invalid number");
}
```

In this example, the `+str`

expression attempts to convert the string to a number, but since the string "not a number" is not a valid number, the `Number.isNaN()`

function will return true.

Method 7: Using `Math.trunc()`

function

The `Math.trunc()`

function can be used to convert a floating-point number to an integer by removing its decimal part. Here's an example:

```
let num = 3.14;
let int = Math.trunc(num);
console.log(int); // 3
```

In this example, the `Math.trunc()`

function is used to convert the floating-point number `3.14`

to the integer `3`

.

Method 8: Using `Math.round()`

function

The `Math.round()`

function can be used to round a floating-point number to the nearest integer. Here's an example:

```
let num = 3.5;
let rounded = Math.round(num);
console.log(rounded); // 4
```

In this example, the `Math.round()`

function is used to round the floating-point number `3.5`

to the nearest integer, which is `4`

.

Method 9: Using `Math.floor()`

function

The `Math.floor()`

function can be used to round a floating-point number down to the nearest integer. Here's an example:

```
let num = 3.9;
let floor = Math.floor(num);
console.log(floor); // 3
```

In this example, the `Math.floor()`

function is used to round the floating-point number `3.9`

down to the nearest integer, which is `3`

.

Method 10: Using `Math.ceil()`

function

The `Math.ceil()`

function can be used to round a floating-point number up to the nearest integer. Here's an example:

```
let num = 3.1;
let ceil = Math.ceil(num);
console.log(ceil); // 4
```

In this example, the `Math.ceil()`

function is used to round the floating-point number `3.1`

up to the nearest integer, which is `4`

.

In conclusion, TypeScript provides several ways to convert a string to a number, including parseInt(), parseFloat(), + operator, Number() function, ~~ operator, Math.trunc(), Math.round(), Math.floor() and Math.ceil() functions. Additionally, Number.isNaN() function can be used to check if a value is a valid number before converting it. Each method has its own set of advantages and disadvantages, so it's important to choose the right method depending on the specific use case.

When working with numbers, it's important

## Popular questions

- What is the difference between parseInt() and parseFloat() in TypeScript?

- The parseInt() function is used to convert a string to an integer, while the parseFloat() function is used to convert a string to a floating-point number.

- What is the advantage of using the + operator to convert a string to a number in TypeScript?

- The + operator is a quick and simple way to convert a string to a number in TypeScript, and it only works if the string contains numeric characters.

- How can you check if a value is a valid number before converting it in TypeScript?

- The Number.isNaN() function can be used to check if a value is not a number before converting it.

- What is the difference between Math.trunc() and Math.round() in TypeScript?

- Math.trunc() function is used to convert a floating-point number to an integer by removing its decimal part, while Math.round() function is used to round a floating-point number to the nearest integer.

- How can you convert a string to a number in TypeScript and round it up to the nearest integer?

- You can use the Math.ceil() function to round a number up to the nearest integer after converting the string to a number using any of the above-mentioned methods like + operator, parseInt(), Number() function, etc.

### Tag

Conversion.