fluentreports/lib/third-party/blob.js

A simple, Fluent API for creating PDF Reports

// License MIT
// https://github.com/webmodules/blob
/**
 * Create a blob builder even when vendor prefixes exist
 */

var BlobBuilder = global.BlobBuilder
    || global.WebKitBlobBuilder
    || global.MSBlobBuilder
    || global.MozBlobBuilder;

/**
 * Check if Blob constructor is supported
 */

var blobSupported = (function() {
    try {
        var a = new Blob(['hi']);
        return a.size === 2;
    } catch(e) {
        return false;
    }
})();

/**
 * Check if Blob constructor supports ArrayBufferViews
 * Fails in Safari 6, so we need to map to ArrayBuffers there.
 */

var blobSupportsArrayBufferView = blobSupported && (function() {
    try {
        var b = new Blob([new Uint8Array([1,2])]);
        return b.size === 2;
    } catch(e) {
        return false;
    }
})();

/**
 * Check if BlobBuilder is supported
 */

var blobBuilderSupported = BlobBuilder
    && BlobBuilder.prototype.append
    && BlobBuilder.prototype.getBlob;

/**
 * Helper function that maps ArrayBufferViews to ArrayBuffers
 * Used by BlobBuilder constructor and old browsers that didn't
 * support it in the Blob constructor.
 */

function mapArrayBufferViews(ary) {
    return ary.map(function(chunk) {
        if (chunk.buffer instanceof ArrayBuffer) {
            var buf = chunk.buffer;

            // if this is a subarray, make a copy so we only
            // include the subarray region from the underlying buffer
            if (chunk.byteLength !== buf.byteLength) {
                var copy = new Uint8Array(chunk.byteLength);
                copy.set(new Uint8Array(buf, chunk.byteOffset, chunk.byteLength));
                buf = copy.buffer;
            }

            return buf;
        }

        return chunk;
    });
}

function BlobBuilderConstructor(ary, options) {
    options = options || {};

    var bb = new BlobBuilder();
    mapArrayBufferViews(ary).forEach(function(part) {
        bb.append(part);
    });

    return (options.type) ? bb.getBlob(options.type) : bb.getBlob();
};

function BlobConstructor(ary, options) {
    return new Blob(mapArrayBufferViews(ary), options || {});
};

if (global.Blob) {
    BlobBuilderConstructor.prototype = Blob.prototype;
    BlobConstructor.prototype = Blob.prototype;
}

module.exports = (function() {
    if (blobSupported) {
        return blobSupportsArrayBufferView ? global.Blob : BlobConstructor;
    } else if (blobBuilderSupported) {
        return BlobBuilderConstructor;
    } else {
        return undefined;
    }
})();