speedy-entities/escapeXML.js

The fastest XML/HTML entities decoder.

const re = /["&'<>]/g;
export function escapeXML(input) {
    let output = '';
    let textIndex = 0;
    while (re.test(input)) {
        const lastIndex = re.lastIndex;
        const startIndex = lastIndex - 1;
        const charCode = input.charCodeAt(startIndex);
        let entity;
        if (charCode === 34) {
            entity = '&quot;';
        }
        else if (charCode === 38) {
            entity = '&amp;';
        }
        else if (charCode === 39) {
            entity = '&apos;';
        }
        else if (charCode === 60) {
            entity = '&lt;';
        }
        else {
            entity = '&gt;';
        }
        output += textIndex === startIndex ? entity : input.slice(textIndex, startIndex) + entity;
        textIndex = lastIndex;
    }
    return textIndex === 0 ? input : textIndex === input.length ? output : output + input.slice(textIndex);
}