construct-js

construct-js 介绍

construct-js是一个用于创建字节级数据结构的库。它侧重于声明性API和使用简单性。

安装

npm i construct-js

示例  

以下示例构建一个完全有效的zip存档，其中包含一个文件 - helloworld.txt。

const fs = require('fs');

const {

RawString,

U16,

U32,

Struct,

} = require('construct-js');

const data = RawString('helloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworldhelloworld');

const filename = RawString('helloworld.txt');

const sharedHeaderInfo = Struct('sharedHeaderInfo')

.field('minVersion',U16(10))

.field('gpFlag',U16(0))

.field('compressionMethod',U16(0))

.field('lastModifiedTime',U16(0))

.field('lastModifiedDate',U16(0))

.field('crc32',U32(0))

.field('compressedSized',U32(data.byteLength))

.field('uncompressedSized',U32(data.byteLength))

.field('filenameSize',U16(filename.byteLength))

.field('extraFieldLength',U16(0));

const localHeader = Struct('localHeader')

.field('header',U32(0x04034b50))

.field('sharedHeaderInfo',sharedHeaderInfo)

.field('filename',filename);

const centralDirectory = Struct('centralDirectory')

.field('header',U32(0x02014b50))

.field('madeByVersion',U16(10))

.field('sharedHeaderInfo',sharedHeaderInfo)

.field('fileCommentSize',U16(0))

.field('diskNumber',U16(0))

.field('internalFileAttributes',U16(0))

.field('externalFileAttributes',U32(0))

.field('relativeOffset',U32(0))

.field('filename',filename);

const endOfCentralDirectory = Struct('endOfCentralDirectory')

.field('header',U32(0x06054b50))

.field('diskNumber',U16(0))

.field('centralDirdiskStart',U16(0))

.field('numberOfCentralDirsOndisk',U16(1))

.field('totalNumberOfCentralDirs',U16(1))

.field('centralDirsize',U32(0))

.field('offsetToStart',U32(0))

.field('commentLength',U16(0));

const zipFile = Struct('ZipFile')

.field('localHeader',localHeader)

.field('data',data)

.field('centralDirectory',centralDirectory)

.field('endOfCentralDirectory',endOfCentralDirectory);

const offset = zipFile.getoffset('centralDirectory');

endOfCentralDirectory.get('offsetToStart').set(offset);

const filebuffer = zipFile.toBuffer();

fs.writeFile('./test.zip',filebuffer,() => {});

GitHub:https://github.com/francisrstokes/construct-js

网站描述:一个用于创建字节级别数据结构的库

construct-js

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