您如何“结束"运行大口吃任务，但仅在当前任务结束时? [英] How do you run a gulp "on end" task but only at the end of the current task?

问题描述

我正在使用Gulp收集前题(通过gulp-front-matter插件)，然后在对其进行汇总之后，将其保存到另一个文件中.在其他数据中，我节省了很多CSS.这是我为compileCSS任务准备的东西:

I'm using Gulp to collect front-matter (via gulp-front-matter plugin) and then, after aggregating it, I'm saving it into another file. Among other data, I'm saving a bunch of CSS. Here's what I have for my compileCSS task:

var collected = [];

gulp.src('./client/**/*.html')
  .pipe(frontMatter({ property: 'meta', remove: true }))
  .pipe(through.obj(function(file, enc, callback) {
       var css = file.meta;
       collected.push(css);
   }))
   .pipe(gulp.dest('./build/templates'))
   .on('end', function() {
       var cssPath = ['build', 'assets', 'css', 'compiled.css'];
       fs.writeFileSync(cssPath.join(path.sep), cssPath);
   })

;

任务按预期方式工作(请注意，它是简化版本).一切都按预期工作，我得到了一个包含所有前端CSS的compiled.css文件.但是，我发现不仅需要在我的常规CSS文件中使用Prefixer，而且还需要在这个新的named.css中使用Prefixer.所以我创建了一个prefix任务:

The task works as expected (note, it's a simplified version). Everything works as expected and I get a compiled.css file with all of the front-matter CSS. However, I found a need to use the Prefixer not only on my regular css file but on this new compiled.css as well. So I created a prefix task:

gulp.task('prefix', ['compileCSS', 'copy'], function() {
    gulp.src('./build/assets/css/*.css')
        .pipe(autoprefixer({ browsers: ['last 3 versions'] }))
        .pipe(gulp.dest('build'))
    ;
});

现在，问题在于on('end'函数在所有任务(而不只是compileCSS任务)的末尾运行.

Now, the problem is that the on('end' function runs at the end of ALL the tasks, not just the compileCSS task.

我的问题是，有没有办法为每个任务注入结束"类型的任务?还是有一种以某种方式使用流的方法(由于上一个任务不是实际的流，并且没有利用它，所以我不知道如何使用它.)

My question is, is there a way to inject an "on end" type task for each task? Or is there a way to use streams somehow (since the last task isn't an actual stream and doesn't take advantage of it, I don't see how).

推荐答案

这不是问题所在，我没有返回创建竞争条件的流，所以这样的修复起作用了:

It wasn't the sequence that was the problem, I wasn't returning the stream which created a race condition so a fix like this worked:

return gulp.src('./client/**/*.html')
          .pipe(dosomething());
  \\ all other code

我想问题是Gulp在开始下一个事件之前等待流完成.在不返回流或承诺的情况下，Gulp只会运行任务，而不会等待其完成.

I guess the problem was that Gulp waits for a stream to be done before setting off the next event. Without returning streams or promises, Gulp simply runs the task and doesn't wait for it to finish.

这篇关于您如何“结束"运行大口吃任务，但仅在当前任务结束时?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！