Css string to int

5 Ways to Convert HTML Strings to Integers in JavaScript: Best Practices and Tips

Learn how to convert HTML strings to integers in JavaScript with 5 different methods. From parseInt() to parseFloat(), discover best practices and common issues to avoid.

• Using parseInt() function
• Using Number() constructor
• Javascript How To Convert String To Number Tutorial
• Using Unary operator(+)
• Using Math.floor() function
• Using parseFloat() method
• Other useful JavaScript code snippets for converting HTML strings to integers
• Conclusion
• How to convert HTML text to number in JavaScript?
• How to convert string to int in HTML?
• How do I turn a string into an integer?
• Which method is used to convert a number in string to an integer in JS?

JavaScript is a widely-used programming language that is commonly used for web development. One of the most common tasks in JavaScript is to convert strings to integers. In this blog post, we will explore the different ways of converting HTML strings to integers in JavaScript, including the parseInt() function, Number() constructor, Unary operator(+), Math.floor() function, and parseFloat() method. We will also discuss best practices and common issues related to this task.

Using parseInt() function

The parseInt() function is one of the most commonly used methods of converting a string to an integer in javascript. To use it, you simply pass the string value as an argument to the parseInt() method. The method also accepts a second parameter, which is the radix or base of the number system you want to convert to.

let num = parseInt("10"); console.log(num); // 10 

The parseInt() method returns a number value. However, if the value entered cannot be converted to a number, it returns NaN.

let num = parseInt("10a"); console.log(num); // NaN 

One of the advantages of using parseInt() is its ability to handle negative numbers.

let num = parseInt("-10"); console.log(num); // -10 

However, one of the disadvantages of using parseInt() is its inability to handle decimal values. It also relies on the radix parameter, which can result in unexpected results if not used correctly.

To avoid these issues, it is advisable to always specify the radix parameter when using parseInt(). You should also check for NaN values after conversion.

let num = parseInt("10", 10); if (isNaN(num))  console.log("Input value is not a number"); > else  console.log(num); > 

Using Number() constructor

The Number() constructor is another method of converting a string to a number in javascript. It is similar to parseInt() in that it can handle decimal values. However, it does not support the radix parameter.

let num = Number("10.5"); console.log(num); // 10.5 

Like parseInt(), Number() also returns NaN if the value entered cannot be converted to a number.

let num = Number("10a"); console.log(num); // NaN 

One of the advantages of using Number() is its ability to handle decimal values.

let num = Number("10.5"); console.log(num); // 10.5 

However, one of the disadvantages of using Number() is its inability to handle negative numbers.

let num = Number("-10"); console.log(num); // -10 

Javascript How To Convert String To Number Tutorial

In this tutorial you’ll learn how to learn how to use JavaScript to convert a string to a number Duration: 4:00

Using Unary operator(+)

The Unary operator(+) is another method of converting a string to an integer in JavaScript. It is a shorthand for the Number() constructor.

let num = +"10"; console.log(num); // 10 

Like Number(), the Unary operator(+) can handle decimal values.

let num = +"10.5"; console.log(num); // 10.5 

However, like Number(), it also cannot handle negative numbers.

let num = +"-10"; console.log(num); // NaN 

Using Math.floor() function

The Math.floor() function is another way of converting a string to a number in JavaScript. It rounds the number down to the nearest integer.

let num = Math.floor("10.5"); console.log(num); // 10 

Like parseInt() and Number(), Math.floor() also returns NaN if the value entered cannot be converted to a number.

let num = Math.floor("10a"); console.log(num); // NaN 

One of the advantages of using Math.floor() is its ability to round down to the nearest integer.

let num = Math.floor("10.9"); console.log(num); // 10 

However, one of the disadvantages of using Math.floor() is its inability to handle decimal values or negative numbers.

Using parseFloat() method

The parseFloat() method is another method of converting a string to a number in JavaScript. It parses a value as a string and returns the first number.

let num = parseFloat("10.5"); console.log(num); // 10.5 

Like Number(), parseFloat() can handle decimal values.

let num = parseFloat("10.5"); console.log(num); // 10.5 

However, like parseInt() and Number(), parseFloat() also returns NaN if the value entered cannot be converted to a number.

let num = parseFloat("10a"); console.log(num); // NaN 

One of the advantages of using parseFloat() is its simplicity.

let num = parseFloat("10.5"); console.log(num); // 10.5 

However, like parseInt() and Number(), parseFloat() cannot handle negative numbers.

Other useful JavaScript code snippets for converting HTML strings to integers

In Javascript as proof, Javascript string to int code example

var myInt = parseInt("10.256"); //10 var myFloat = parseFloat("10.256"); //10.256

In Javascript , Convert a string to an integer in Javascript code example

// try using parsInt(x) // you can then use typeof(x) to confirm var myString = "555"; var myInt = parseInt(string); console.log(typeof myInt); // number

In Javascript , for instance, string to int javascript code sample

var text = '42px'; var integer = parseInt(text, 10); // returns 42 let myNumber = Number("5.25"); //5.25

In Javascript , for example, javascript string to integer code sample

In Javascript as proof, javascript string to integer code sample

var string = "10"; var integer = parseInt(string); console.log(typeof(integer)); // int

In Javascript , for example, string to int javascript code example

var text = '42px'; var integer = parseInt(text, 10); // returns 42 

In Javascript , in particular, How to convert a string to an integer in javascript? code example

In Javascript as proof, string to int javascript code sample

var text = '3.14someRandomStuff'; var pointNum = parseFloat(text); // returns 3.14 

JavaScript parseInt() Function var a = parseInt(String) var a = parseInt("10")

In Javascript , for instance, string to int in javascript code example

var a=15 const doubleToInt=parseInt(15.15) const intToFloat=a.toFixed(2) var a="1546" const stringToInt=parseInt(a)

Conclusion

Converting strings to integers is an important task for developers working with JavaScript. In this blog post, we have explored the different ways of converting HTML strings to integers in JavaScript, including the parseInt() function, Number() constructor, Unary operator(+), Math.floor() function, and parseFloat() method. We have also discussed best practices and common issues related to this task.

To summarize, it is important to always specify the radix parameter when using parseInt(), check for NaN values after conversion, and be aware of the limitations of each method when converting strings to numbers in javascript.

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7 ways to convert a String to Number in JavaScript

parseInt() parses a string and returns a whole number. Spaces are allowed. Only the first number is returned.
This method has a limitation though. If you parse the decimal number, it will be rounded off to the nearest integer value and that value is converted to string. One might need to use parseFloat() method for literal conversion.

myString = '129' console.log(parseInt(myString)) // expected result: 129 a = 12.22 console.log(parseInt(a)) // expected result: 12 

2. Using Number()

Number() can be used to convert JavaScript variables to numbers. We can use it to convert the string too number.
If the value cannot be converted to a number, NaN is returned.

Number("10"); // returns 10 Number(" 10 "); // returns 10 Number("10.33"); // returns 10.33 

3. Using Unary Operator (+)

The unary plus operator ( + ) precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn’t already.

const x = 25; const y = -25; console.log(+x); // expected output: 25 console.log(+y); // expected output: -25 console.log(+''); // expected output: 0 

4. Using parseFloat()

parseFloat() parses a string and returns a number. Spaces are allowed. Only the first number is returned.

parseFloat("10"); // returns 10 parseFloat("10.33"); // returns 10.33 parseFloat("10 20 30"); // returns 10 parseFloat("10 years"); // returns 10 parseFloat("years 10"); // returns NaN 

5. Using Math.floor()

The Math.floor() function returns the largest integer less than or equal to a given number. This can be little tricky with decimal numbers since it will return the value of the nearest integer as Number.

str = '1222' console.log(Math.floor(str)) // returns 1222 a = 12.22 Math.floor(a) // expected result: 12 

6. Multiply with number

Multiplying the string value with the 1 which won’t change the value and also it will be converted to number by default.

str = '2344' console.log(str * 1) // expected result: 2344 

7. Double tilde (~~) Operator

str = '1234' console.log(~~str) // expected result: 1234 negStr = '-234' console.log(~~negStr) // expected result: -234 

Here is the comparison of the ways mentioned performance wise. Comment below if you know more methods.
Thank You

Top comments (17)

The double tilde method is actually something I never thought about, but is worth explaining.

The double tilde «operator» is not as much as an operator as it’s a double bitwise negation.

Let’s cast ’64’ to 64 using this method, so we do ~~’64’ . First we will evaluate ~’64’ . As bitwise operations work on binary, ’64’ is cast to a number. So ~64 .

64 in binary is 01000000 . ~ will negate all the bits so it becomes 10111111 , which is -65 since numbers in JavaScript are signed. Now we negate it again, which becomes 01000000 , which is 64 in decimal.

I previously stated that 10111111 is -63 , which is incorrect. It’s actually -65 . Sorry about that.

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