Remove all Non-ASCII characters from the string using JavaScript

Last Updated : 8 Sep, 2026

JavaScript provides several ways to remove non-ASCII characters from a string. Regular expressions can directly match characters outside the ASCII range, while array methods can filter characters based on their character codes.

  • ASCII characters have character codes from 0 to 127.
  • Use replace() with a regular expression to remove non-ASCII characters directly.
  • Use filter() and charCodeAt() when you want to process each character individually.

Approach 1: Using ASCII Values in Regular Expression

A regular expression can match every character outside the ASCII range using [^\x00-\x7F]. The replace() method then replaces these characters with an empty string.

Example: In this example, we remove all characters whose ASCII values are greater than 127.

JavaScript 
// Input String
let str = "Hidd©©©en??Ascii ©©®®®Charac££ter";

// Display input string
console.log(str);

// Remove non-ASCII characters
function gfg_Run() {
    str = str.replace(/[^\x00-\x7F]/g, "");

    // Display output
    console.log(str);
}

// Function call
gfg_Run();

Approach 2: Using Unicode Range in Regular Expression

Unicode escape sequences can also be used to identify characters outside the ASCII range. The range \u{0080}-\u{FFFF} represents characters starting from code point 128.

Example: In this example, we use a Unicode regular expression to remove non-ASCII characters.

JavaScript 
// Input String
let str = "Hidd©©©en??Ascii ©©®®®Charac££ter";

// Display input string
console.log(str);

// Remove non-ASCII characters
function gfg_Run() {
    str = str.replace(/[\u{0080}-\u{FFFF}]/gu, "");

    // Display output
    console.log(str);
}

// Function call
gfg_Run();
  • \u{0080}-\u{FFFF} represents the specified Unicode range above ASCII.
  • The u flag enables Unicode-aware matching.
  • The g flag removes all matching characters.

Note: This pattern does not cover every Unicode code point above U+FFFF. For a general solution that removes everything outside ASCII, the [^\x00-\x7F] pattern is preferable.

Approach 3: Using ASCII Values with filter()

The filter() method can be combined with split() and charCodeAt() to keep only characters whose ASCII codes are between 0 and 127.

Example: In this example, we split the string into individual characters and filter out characters with ASCII values greater than 127.

JavaScript 
// Input String
let str = "Hidd©©©en??Ascii ©©®®®Charac££ter";

// Display input string
console.log(str);

// Remove non-ASCII characters
function gfg_Run() {
    str = str
        .split("")
        .filter(function (char) {
            return char.charCodeAt(0) <= 127;
        })
        .join("");

    // Display output
    console.log(str);
}

// Function call
gfg_Run();

Approach 4: Using replace() with a Custom Function

A reusable function can be created around the replace() method. This makes the operation easier to use with multiple strings.

Example: In this example, we create a custom removeNonASCII() function to remove all non-ASCII characters.

JavaScript 
// Input String
let str = "Hidd©©©en??Ascii ©©®®®Charac££ter";

// Display input string
console.log(str);

// Function to remove non-ASCII characters
function removeNonASCII(input) {
    return input.replace(/[^\x00-\x7F]/g, "");
}

// Remove non-ASCII characters
function gfg_Run() {
    str = removeNonASCII(str);

    // Display output
    console.log(str);
}

// Function call
gfg_Run();
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