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How to convert string into float in JavaScript?

Last Updated : 12 Jul, 2025
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In this article, we will convert a string into a float in Javascript. We can convert a string into a float in JavaScript by using some methods which are described below:

Methods to Concert String into Float:

Table of Content


Method 1: By using Type Conversion of JavaScript

In this method, we will use the Type Conversion feature of JavaScript which will convert the string value into float.

Example: Below program demonstrates the above approach 

javascript 
// Javascript script
// to convert string
// to float value

// Function to convert
// string to float value
function convert_to_float(a) {

    // Type conversion
    // of string to float
    let floatValue = +a;

    // Return float value
    return floatValue;
}

//Driver code
let n = "55.225";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
    " Type of " + n + " = " + typeof n);

n = "-33.565";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

Output
Converted value = 55.225 Type of 55.225 = number
Converted value = -33.565 Type of -33.565 = number

Method 2: By using parseFloat() Method

In this method, we will use the parseFloat() method which is an inbuilt function in JavaScript that is used to accept the string and convert it into a floating point number. If the string does not contain a numeral value or If the first character of the string is not a Number then it returns NaN i.e, not a number. 

Example: Below program demonstrates the above approach 

javascript 
// Javascript script
// to convert string
// to float value

// Function to convert
// string to float value
function convert_to_float(a) {

    // Using parseFloat() method
    let floatValue = parseFloat(a);

    // Return float value
    return floatValue;
}

//Driver code
let n = "245.165";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);
n = "-915.55";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

Output
Converted value = 245.165 Type of 245.165 = number
Converted value = -915.55 Type of -915.55 = number


Special Case: In French, float numbers are written by the use of a comma (, ) as a separator instead of a dot(.) as a separator.

Example:

The value 245.67 in French is written as 245, 67

To convert a French string into a float in JavaScript we will first use replace() method to replace every (, ) with (.) then follow any of the above-described methods. 

Example: Below program demonstrates the above approach 

javascript 
// Javascript script
// to convert string
// to float value

// Function to convert
// string to float value
function convert_to_float(a) {
    // Using parseFloat() method
    // and using replace() method
    // to replace ', ' with '.'
    let floatValue = parseFloat(a.replace(/, /, "."));

    // Return float value
    return floatValue;
}

//Driver code
let n = "245, 165";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

n = "-915, 55";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

Output
Converted value = 245.165 Type of 245.165 = number
Converted value = -915.55 Type of -915.55 = number

Method 3: By using the eval() function

In this method, we will use the eval() method which is an inbuilt function in JavaScript that is used to evaluate the string return result. If the string contains a number then it converts it from string to number and then returns it and if contains other than the number it returns NaN i.e, not a number. Example: Below program demonstrates the above approach 

JavaScript 
// Javascript script
// to convert string
// to float value

// Function to convert
// string to float value
function convert_to_float(a) {
    // Type conversion
    // of string to float
    let floatValue = eval(a);

    // Return float value
    return floatValue;
}

//Driver code
let n = "55.225";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

n = "-33.565";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

Output
Converted value = 55.225 Type of 55.225 = number
Converted value = -33.565 Type of -33.565 = number

Method 4: By using Number() constructor

In this method, we can use the Number() constructor which is a built-in function in JavaScript to convert a string into a number, including floats. It parses the argument as a float (or integer) and returns the result.

Example:

JavaScript 
// Using Number() constructor to convert a string into a float
let stringNumber = "3.14";
let floatNumber = Number(stringNumber);
console.log(floatNumber); // Output: 3.14

Output
3.14

Method 5: By using Unary Plus Operator

The unary plus (+) operator can be used to convert a string to a number, including floats. It is a simple and concise way to perform this conversion.

Example: Below program demonstrates the above approach

JavaScript 
// Javascript script
// to convert string
// to float value

// Function to convert
// string to float value
function convert_to_float(a) {
    // Using unary plus operator
    let floatValue = +a;

    // Return float value
    return floatValue;
}

//Driver code
let n = "123.456";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

n = "-789.012";

// Call function
n = convert_to_float(n);

// Print result
console.log("Converted value = " + n +
        " Type of " + n + " = " + typeof n);

Output
Converted value = 123.456 Type of 123.456 = number
Converted value = -789.012 Type of -789.012 = number



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