如何将参数从 gulp 观察者传递到任务

Question

如果我有这样的观察者：

gulp.watch('js/**/*.js').on('change', path => {
gulp.series(build, reload)();
});

。任务build如下所示：

const build = done => {
return gulp
.src(path) // Use "path" here
.pipe(
rename({
dirname: ''
})
)
.pipe(uglify())
.pipe(gulp.dest('build'));
};

如何将path参数传递给build任务？

Answer 1

作为一项练习，我相信我得到了你想要的工作。 但首先让我说，限制源管道的传统方法是使用类似gulp-newer的东西。 你应该看看这是否实现了你想要的。

但这里有一些可能对你有用的东西[没有经过很好的测试！

function build (path)  {
return new Promise(resolve => {
// using setTimeout() to prove async/await is working as expected
setTimeout(() => {
resolve('resolved');
}, 2000);
// put your gulp.src pipeline here using 'path'
console.log("2 path = " + path);
});
};
function anotherTask (path)  {
return new Promise(resolve => { 
// put your gulp.src pipeline here
console.log("4 path = " + path); });
};
function testWatch () {
console.log("in testWatch");
// debounceDelay because gulp likes to call the watcher 2 or 3times otherwise
//  see [gulp watch task running multiple times when a file is saved][2]
var watcher = gulp.watch('js/**/*.js', { debounceDelay: 2000 });
// I added the async/await because I wasn't sure those functions would be run in series
//  as you wanted.
// With the event listener route I couldn't get gulp.series to work, 
//  so went with async/await.
watcher.on('change', async function(path, stats) {
console.log('1 File ' + path + ' was changed');
await build(path);
console.log("3 after build");
// I would assume that the **last** task in the chain doesn't need 'await'
// or to return a promise as in anotherTask
await anotherTask(path);
console.log("5 after anotherTask");
});
};
gulp.task('default', gulp.series(testWatch));

Gulp Watch 在代码中多次运行上面提到的。

输出(我的js手表src与你的不同(：

in testWatch
1 File srcjsmain.js was changed
2 path = srcjsmain.js
3 after build
4 path = srcjsmain.js
5 after anotherTask
1 File srcjstaxonomy.js was changed
2 path = srcjstaxonomy.js
3 after build
4 path = srcjstaxonomy.js
5 after anotherTask