index.js 1.8 KB
/**
 * Returns a `Buffer` instance from the given data URI `uri`.
 *
 * @param {String} uri Data URI to turn into a Buffer instance
 * @returns {Buffer} Buffer instance from Data URI
 * @api public
 */
export function dataUriToBuffer(uri) {
    if (!/^data:/i.test(uri)) {
        throw new TypeError('`uri` does not appear to be a Data URI (must begin with "data:")');
    }
    // strip newlines
    uri = uri.replace(/\r?\n/g, '');
    // split the URI up into the "metadata" and the "data" portions
    const firstComma = uri.indexOf(',');
    if (firstComma === -1 || firstComma <= 4) {
        throw new TypeError('malformed data: URI');
    }
    // remove the "data:" scheme and parse the metadata
    const meta = uri.substring(5, firstComma).split(';');
    let charset = '';
    let base64 = false;
    const type = meta[0] || 'text/plain';
    let typeFull = type;
    for (let i = 1; i < meta.length; i++) {
        if (meta[i] === 'base64') {
            base64 = true;
        }
        else {
            typeFull += `;${meta[i]}`;
            if (meta[i].indexOf('charset=') === 0) {
                charset = meta[i].substring(8);
            }
        }
    }
    // defaults to US-ASCII only if type is not provided
    if (!meta[0] && !charset.length) {
        typeFull += ';charset=US-ASCII';
        charset = 'US-ASCII';
    }
    // get the encoded data portion and decode URI-encoded chars
    const encoding = base64 ? 'base64' : 'ascii';
    const data = unescape(uri.substring(firstComma + 1));
    const buffer = Buffer.from(data, encoding);
    // set `.type` and `.typeFull` properties to MIME type
    buffer.type = type;
    buffer.typeFull = typeFull;
    // set the `.charset` property
    buffer.charset = charset;
    return buffer;
}
export default dataUriToBuffer;
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