generic-filehandle2/esm/blobFile.js

uniform interface for accessing binary data from local files, remote HTTP resources, and browser Blob data

/**
 * Blob of binary data fetched from a local file (with FileReader).
 *
 * Adapted by Robert Buels and Garrett Stevens from the BlobFetchable object in
 * the Dalliance Genome Explorer, which is copyright Thomas Down 2006-2011.
 */
export default class BlobFile {
    constructor(blob) {
        this.blob = blob;
        this.size = blob.size;
    }
    async read(length, position = 0) {
        // short-circuit a read of 0 bytes here, because browsers actually sometimes
        // crash if you try to read 0 bytes from a local file!
        if (!length) {
            return new Uint8Array(0);
        }
        const start = position;
        const end = start + length;
        return new Uint8Array(await this.blob.slice(start, end).arrayBuffer());
    }
    async readFile(options) {
        const encoding = typeof options === 'string' ? options : options?.encoding;
        if (encoding === 'utf8') {
            return this.blob.text();
        }
        else if (encoding) {
            throw new Error(`unsupported encoding: ${encoding}`);
        }
        else {
            return new Uint8Array(await this.blob.arrayBuffer());
        }
    }
    async stat() {
        return { size: this.size };
    }
    async close() {
        return;
    }
}
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