Convert String to Number in Typescript
Working with string data in any programming language is often an essential part of the development process. However, sometimes it becomes necessary to convert a string value into a numerical value, and this is where the Convert String to Number function comes in handy. In Typescript, this function is used to convert a string value into a numeric data type.
Why We Need to Convert a String to Number in Typescript?
Converting a string value to a number is essential because many JavaScript operations involve calculating numeric values. Suppose you want to add two variables, the operator expects a numeric data type. Therefore, if the user enters a value as a string, it needs to convert it to a number to perform mathematical operations or calculate results.
In other cases, some APIs may return string data type instead of intended numerical data types. Some other common use cases include converting user input from a web interface or converting data from databases that may store numbers as strings.
Typescript Convert String to Number Methods
The Typescript library provides several ways to convert a string to a number. Let’s take a look at some of these methods:
Method 1: Using parseInt()
The parseInt() method parses a string and returns an integer. This method takes two arguments, including the string value to convert and the base integer value.
Here is an example of the parseInt() method:
“`
const numString: string = “10”;
const num: number = parseInt(numString, 10);
console.log(num);
“`
The first line of the example defines a string variable containing the value “10.” The next line calls the parseInt() method to convert the string into an integer and assigns that integer to a variable named “num.” The third line logs the resulting number to the console, which should output “10.”
Method 2: Using parseFloat()
The parseFloat() method parses a string and returns a floating-point number. This method takes only one argument, the string value to be converted.
The following is an example of the parseFloat() method:
“`
const numString: string = “7.5”;
const num: number = parseFloat(numString);
console.log(num);
“`
The first line of the example defines a string variable containing the value “7.5.” The next line calls the parseFloat() method to convert the string into a floating-point number and assigns that number to a variable named “num.” The third line logs the resulting number to the console, which should output “7.5.”
Method 3: Using the Unary Operator
The Unary operator (+) is a concise way of converting a string to a number. This method works by using the plus operator to convert a string to a number.
Here is an example of using the unary operator:
“`
let numString: string = “9”;
let num: number = +numString;
console.log(num);
“`
The first line of the code defines a string variable containing the value “9.” The second line uses the unary operator to convert the string into a number and assigns the number to a variable named “num.” The third line logs the resulting number to the console, which should output “9.”
FAQs
What happens if a string cannot be converted to a number?
If a string cannot be converted to a number using any of the methods above, you will get a NaN (Not a Number) value.
Can I convert a negative string to a number?
Yes. When using parseInt() or parseFloat(), negative numbers can be converted without any issues. You can add a “-” sign before the number to convert the negative string. For instance, let str=”-10″, parseInt(str) will output -10.
What is the best way to convert a string to a number in Typescript?
That depends on your use case. If you already know that the string represents an integer value, you can use the parseInt() method. However, if the string represents a floating-point value, you should use the parseFloat() method.
What is the difference between parseInt() and parseFloat() in Typescript?
ParseInt() function returns an integer number. If the string value has a decimal part, it will be truncated. parseFloat(), on the other hand, returns a floating point number, and the decimal values are maintained.
Final Thoughts
Converting a string to a number is a common operation when dealing with user input or data from external sources. In Typescript, you have several methods to do this, including parseInt() and parseFloat(). Each method has its use case, and it’s up to you to decide which one is best for your needs.