如何读取stream.pipe（myfunction（））

如何读取stream.pipe（myfunction（）） ？

我尝试，但给错误。 如何读取gulp.src（'./ userdata.json'）和.pipe（）的stream ？ 我不知道它是如何做的。

gulpfile.js

var upmodul = require("modul-json"); //...... return gulp.src('./userdata.json') .pipe(upmodul()); ......// 

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node_modules / modul-json / index.js

 'use strict'; var Stream = require('stream'); var loger = function () { var readable = new Stream.Readable({ read: function (n) { this.push("ll"); } }); } module.exports = loger; 

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错误

  [00:19:39] TypeError: Cannot read property 'on' of undefined at DestroyableTransform.Readable.pipe (E:\Developers\WebDeveloper\OpenServer -WebProg\domains\progectapi2\node_modules\vinyl-fs\node_modules\readable-stream\ lib\_stream_readable.js:516:7) at Gulp.<anonymous> (E:\Developers\WebDeveloper\OpenServer-WebProg\domains\p rogectapi2\gulpfile.js:159:9) at module.exports (E:\Developers\WebDeveloper\OpenServer-WebProg\domains\pro gectapi2\node_modules\orchestrator\lib\runTask.js:34:7) at Gulp.Orchestrator._runTask (E:\Developers\WebDeveloper\OpenServer-WebProg \domains\progectapi2\node_modules\orchestrator\index.js:273:3) at Gulp.Orchestrator._runStep (E:\Developers\WebDeveloper\OpenServer-WebProg \domains\progectapi2\node_modules\orchestrator\index.js:214:10) at Gulp.Orchestrator.start (E:\Developers\WebDeveloper\OpenServer-WebProg\do mains\progectapi2\node_modules\orchestrator\index.js:134:8) at C:\Users\Tiki \AppData\Roaming\npm\node_modules\gulp\bin\gulp.js:129:20 at nextTickCallbackWith0Args (node.js:433:9) at process._tickCallback (node.js:362:13) at Function.Module.runMain (module.js:432:11) 

Answer 1

gulp文档中有一些关于构build可能对您有用的插件的信息。 只是从该页面的样本谈到转换stream。

所有的gulp插件基本归结为：

 var Transform = require('stream').Transform; module.exports = function() { // Monkey patch Transform or create your own subclass, // implementing `_transform()` and optionally `_flush()` var transformStream = new Transform({objectMode: true}); /** * @param {Buffer|string} file * @param {string=} encoding - ignored if file contains a Buffer * @param {function(Error, object)} callback - Call this function (optionally with an * error argument and data) when you are done processing the supplied chunk. */ transformStream._transform = function(file, encoding, callback) { var error = null, output = doSomethingWithTheFile(file); callback(error, output); }); return transformStream; };