happy-dom/src/utilities/StringUtility.ts

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. It includes many web standards from WHATWG DOM and HTML.

const ASCII_LOWER_CASE_CACHE: Map<string, string> = new Map();
const ASCII_UPPER_CASE_CACHE: Map<string, string> = new Map();

/**
 * String utility.
 */
export default class StringUtility {
	/**
	 * ASCII lowercase.
	 *
	 * @see https://infra.spec.whatwg.org/#ascii-lowercase
	 * @param text Text.
	 * @returns Lowercase text.
	 */
	public static asciiLowerCase(text: string): string {
		const cached = ASCII_LOWER_CASE_CACHE.get(text);
		if (cached) {
			return cached;
		}
		let newText = '';
		for (const char of text) {
			const value = char.charCodeAt(0);
			if (value >= 65 && value <= 90) {
				newText += String.fromCharCode(value + 32);
			} else {
				newText += char;
			}
		}
		ASCII_LOWER_CASE_CACHE.set(text, newText);
		return newText;
	}

	/**
	 * ASCII uppercase.
	 *
	 * @see https://infra.spec.whatwg.org/#ascii-uppercase
	 * @param text Text.
	 * @returns Uppercase text.
	 */
	public static asciiUpperCase(text: string): string {
		const cached = ASCII_UPPER_CASE_CACHE.get(text);
		if (cached) {
			return cached;
		}
		let newText = '';
		for (const char of text) {
			const value = char.charCodeAt(0);
			if (value >= 97 && value <= 122) {
				newText += String.fromCharCode(value - 32);
			} else {
				newText += char;
			}
		}
		ASCII_UPPER_CASE_CACHE.set(text, newText);
		return newText;
	}
}