Validating Strings as Alphanumeric Symbols Using Regex in JavaScript

2025-05-09 2025-05-09

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To check if a string contains only alphanumeric symbols using regular expressions, use ^[ -~]+$. This regular expression matches strings composed of one or more alphanumeric symbols, such as "Hello, world!". If you want to exclude spaces, modify the pattern to ^[!-~]+$.

Additionally, if you want to match a fixed-length alphanumeric string, use the pattern ^[ -~]{n}$. For example, ^[ -~]{6}$ matches a string exactly 6 characters long. You can also specify minimum and maximum lengths to create flexible patterns. For example, to match strings between 12 and 20 characters long, use ^[ -~]{12,20}$.

Below are some commonly used regular expression patterns for validating alphanumeric symbols. Feel free to utilize them as needed.

#	Match Condition	Regular Expression Pattern
1	Contains only alphanumeric symbols	^[ -~]+$
2	Fixed length of n alphanumeric symbols	^[ -~]{n}$
3	At least n alphanumeric symbols	^[ -~]{n,}$
4	No more than m alphanumeric symbols	^[ -~]{1,m}$
5	Between n and m alphanumeric symbols	^[ -~]{n,m}$

A list of common regular expression patterns for validating alphanumeric symbols

Source Code

Below is a JavaScript function designed to check if the input string consists solely of alphanumeric characters and symbols. This function allows verification under the following conditions:

If the minimum length is omitted: The string must consist only of alphanumeric symbols and not exceed the specified maximum length.
If the maximum length is omitted: The string must consist only of alphanumeric symbols and meet the minimum length requirement.
If both minimum and maximum lengths are omitted: The string must consist entirely of alphanumeric symbols.

/**
 * Checks whether a given string consists only of alphanumeric characters and symbols.
 *
 * This function verifies that the string is composed of alphanumeric characters
 * and symbols within the ASCII range (0x20 to 0x7E), and that its length falls
 * within the specified range.
 *
 * @param {string} str The input string.
 * @param {?number} minLength The minimum number of characters (treated as 1 if null).
 * @param {?number} maxLength The maximum number of characters (treated as the length of the string if null).
 * @return {boolean} Returns true if the input string meets the conditions; otherwise, returns false.
 * @throws {Error} Throws an error if the minimum length is less than 1,
 * or if the maximum length is less than the minimum length.
 */
function isAlphanumericSymbols(str, minLength = null, maxLength = null) {
    // Set default values
    const min = minLength === null ? 1 : Number(minLength);
    const max = maxLength === null ? str.length : Number(maxLength);

    // Type checks for input values
    if (isNaN(min)) {
        throw new Error("The minimum length must be an integer.");
    }

    if (isNaN(max)) {
        throw new Error("The maximum length must be an integer.");
    }

    // Validate arguments
    if (min < 1) {
        // Throw an error if the minimum length is less than 1
        throw new Error("The minimum length must be an integer greater than or equal to 1.");
    }

    if (maxLength !== null && max < min) {
        // Throw an error if the maximum length is less than the minimum length
        throw new Error("The minimum length must not exceed the maximum length.");
    }

    // Construct the regular expression pattern for alphanumeric characters and symbols
    const pattern = maxLength === null
        ? new RegExp(`^[ -~]{${min},}$`) // No limit on the maximum number of characters
        : new RegExp(`^[ -~]{${min},${max}}$`);

    // Perform the validation using regular expressions
    return pattern.test(str);
}