How to convert string to float in JavaScript?-JS Tutorial-php.cn

Home

Web Front-end

JS Tutorial

How to convert string to float in JavaScript?

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Aug 25, 2023 pm 12:17 PM

How to convert string to float in JavaScript?

We can convert string to floating point number using parseFloat() function or Number() constructor in JavaScript. Other methods are also available, such as using the operator, eval() and parseInt() methods. Converting a string to a float is a typical operation in JavaScript. This is required when working with numbers represented as strings, such as when reading data from an input field or a CSV file. In this article, we will learn these methods in detail.

Conversion method

In JavaScript, there are multiple ways to convert a string to a floating point number. The most common methods are the parseFloat() function and Number() constructor.

parseFloat() function

The parseFloat function is a tool in JavaScript that helps convert strings into numbers with decimals. You give it a word or sentence and it returns a number. It's easy to use and built into JavaScript.

grammar

The syntax of the parseFloat() function is as follows -

parseFloat(string)

Example

The following is an example of how to use the parseFloat() function -

<!DOCTYPE html>
<html>
<body>
   <p id="demo"></p>
   <script>
      let string = "3.14";
      let float = parseFloat(string);
      document.getElementById("demo").innerHTML = float;
      
      //output:3.14
   </script>
</body>
</html>

Although the parseFloat() function can easily convert strings to floating point numbers, it has some limitations. This function only converts the first part of the string (a valid floating point number). If the floating point number in the string is followed by any non-numeric characters, the function ignores them.

Number() constructor

JavaScript includes a built-in function called Number(), which provides another way to convert a number represented by a string into a floating point number. It returns the equivalent floating point representation of the string sent as input. The Number() function provides a more flexible method of converting strings to floating-point numbers than the parseFloat() function, and it can handle type conversions for a wider variety of data types, including integers and other numeric types.

grammar

The syntax of the Number() constructor is as follows -

new Number(string)

Example

The following is an example of how to use the Number() constructor -

<!DOCTYPE html>
<html>
<body>
   <p id="demo"></p>
   <script>
      let string = "3.114";
      let float = new Number(string);
      document.getElementById("demo").innerHTML = float; //output:3.114
   </script>
</body>
</html>

Although the Number() function is useful for converting strings to floating point numbers, it has some limitations. This function has lower performance than the parseFloat() function and should not be used.

Other methods

There are other ways to convert strings to floats in JavaScript. These methods include using the operator, parseInt() function, and eval() function.

Operator

operator is a simple tool that helps you change words into numbers using floating point numbers as input. Just give it a word that represents a number and it will convert it to a number type called a float. This tool is useful, but it only works with words that are actually numbers. It cannot change words that do not represent numbers.

grammar

The syntax of the operator is as follows -

+string

Example

The following is an example of how to use the operator -

<!DOCTYPE html>
<html>
<body>
   <p id="demo"></p>
   <script>
      let string = "3.4";
      let float = +string;
      document.getElementById("demo").innerHTML = float; //output:3.4
   </script>
</body>
</html>

parseInt() function

parseInt() built-in JavaScript function converts text to an integer or an integer. The parseInt() method accepts a string as input and outputs an integer value. To convert a string to a floating point number, use the ParseInt() function and pass base 10 as an additional argument. Let's look at an example to help us understand.

grammar

The syntax of the parseInt() function is as follows -

parseInt(string, radix)

Example

The following is an example of how to use the parseInt() function to convert a string to a floating point number -

<!DOCTYPE html>
<html>
<body>
   <p id="demo"></p>
   <script>
      let string = "3.4";
      let float = parseInt(string, 10);
      document.getElementById("demo").innerHTML = float; //output:3
   </script>
</body>
</html>

eval() function

The

eval() method is a JavaScript built-in function that evaluates a string into a JavaScript expression. It accepts a string as argument and returns the result, just like the parseInt() function. Converting text to floating point numbers is a common use case for eval(). You can do this by passing a string representing a floating point number as an argument to eval(). Afterwards, the function evaluates the expression and returns a floating point value. Overall, eval() is a useful function for running dynamic code, but should be used with caution to avoid security issues.

grammar

The syntax of the eval() function is as follows -

eval(string)

Example

The following is an example of how to use the eval() function to convert a string to a floating point number -

<!DOCTYPE html>
<html>
<body>
   <p id="demo"></p>
   <script>
      let string = "3.456"; 
      let float = eval(string);
      document.getElementById("demo").innerHTML = float; //output:3.456
   </script>
</body>
</html>

Please note that the eval() function is considered a dangerous function because it can execute any JavaScript code passed to it and may cause security risks if used improperly. Therefore, it is not recommended to use the eval() function to convert a string to a floating point number.

in conclusion

In this blog, we discussed various types of methods to convert strings to numbers. The most common methods are the parseFloat() function and Number() constructor. However, the operator, parseInt() function, and eval() function can also be used to convert strings to floating-point numbers. Each method has its own advantages and disadvantages, and the best method to use will depend on the specific scenario. Developers should understand the limitations of each method and use them accordingly.

The above is the detailed content of How to convert string to float in JavaScript?. For more information, please follow other related articles on the PHP Chinese website!

Statement

This article is reproduced at:tutorialspoint. If there is any infringement, please contact admin@php.cn delete

Node.js Streams with TypeScriptApr 30, 2025 am 08:22 AM

Node.js excels at efficient I/O, largely thanks to streams. Streams process data incrementally, avoiding memory overload—ideal for large files, network tasks, and real-time applications. Combining streams with TypeScript's type safety creates a powe

Python vs. JavaScript: Performance and Efficiency ConsiderationsApr 30, 2025 am 12:08 AM

The differences in performance and efficiency between Python and JavaScript are mainly reflected in: 1) As an interpreted language, Python runs slowly but has high development efficiency and is suitable for rapid prototype development; 2) JavaScript is limited to single thread in the browser, but multi-threading and asynchronous I/O can be used to improve performance in Node.js, and both have advantages in actual projects.

The Origins of JavaScript: Exploring Its Implementation LanguageApr 29, 2025 am 12:51 AM

JavaScript originated in 1995 and was created by Brandon Ike, and realized the language into C. 1.C language provides high performance and system-level programming capabilities for JavaScript. 2. JavaScript's memory management and performance optimization rely on C language. 3. The cross-platform feature of C language helps JavaScript run efficiently on different operating systems.

Behind the Scenes: What Language Powers JavaScript?Apr 28, 2025 am 12:01 AM

JavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.

The Future of Python and JavaScript: Trends and PredictionsApr 27, 2025 am 12:21 AM

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Python vs. JavaScript: Development Environments and ToolsApr 26, 2025 am 12:09 AM

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Is JavaScript Written in C? Examining the EvidenceApr 25, 2025 am 12:15 AM

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript's Role: Making the Web Interactive and DynamicApr 24, 2025 am 12:12 AM

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

See all articles