base64 ＜==＞ Buffer

    /**
     * Transform Data URL to array buffer.
     * @param {string} dataURL - The Data URL to transform.
     * @returns {ArrayBuffer} The result array buffer.
     */

    function dataURLToArrayBuffer(dataURL) {
        var base64 = dataURL.replace(REGEXP_DATA_URL_HEAD, '');
        var binary = atob(base64);
        var arrayBuffer = new ArrayBuffer(binary.length);
        var uint8 = new Uint8Array(arrayBuffer);
        forEach(uint8, function (value, i) {
            uint8[i] = binary.charCodeAt(i);
        });
        return arrayBuffer;
    }
    
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/**
     * Transform array buffer to Data URL.
     * @param {ArrayBuffer} arrayBuffer - The array buffer to transform.
     * @param {string} mimeType - The mime type of the Data URL.
     * @returns {string} The result Data URL.
     */

    function arrayBufferToDataURL(arrayBuffer, mimeType = 'image/jpeg') {
        var chunks = []; // Chunk Typed Array for better performance (#435)

        var chunkSize = 8192;
        var uint8 = new Uint8Array(arrayBuffer);

        while (uint8.length > 0) {
            // XXX: Babel's `toConsumableArray` helper will throw error in IE or Safari 9
            // eslint-disable-next-line prefer-spread
            chunks.push(fromCharCode.apply(null, toArray(uint8.subarray(0, chunkSize))));
            uint8 = uint8.subarray(chunkSize);
        }

        return "data:".concat(mimeType, ";base64,").concat(btoa(chunks.join('')));
    }
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