`gulp-postcss 不是函数` 由 gulp-load-plugins 提供时出现类型错误

Question

我在从 gulp-load-plugins, or incorrectly defined types of gulp-postcss 的类型定义扩展 TypeScirpt 接口 IGulpPlugins 时犯了一些错误。

根据 @types/gulp-load-plugins 的 index.d.ts 中的评论：

/**
 * Extend this interface to use Gulp plugins in your gulpfile.js
 */
interface IGulpPlugins {
}

除 gulp-postcss 之外的所有以下插件都有效。

import * as gulpDebug from 'gulp-debug';
import * as gulpPlumber from 'gulp-plumber';
import * as gulpIntercept from 'gulp-intercept';
import * as gulpIf from 'gulp-if';
import * as gulpPug from 'gulp-pug';
import * aas gulpHtmlPrettify from 'gulp-html-prettify';
import * as gulpSass from 'gulp-sass';
import * as gulpStylus from 'gulp-stylus';
import * as gulpSourcemaps from 'gulp-sourcemaps';
import * as gulpPostCss from 'gulp-postcss';

export interface IGulpPlugins {
  plumber: typeof gulpPlumber;
  debug: typeof gulpDebug;
  intercept: typeof gulpIntercept;
  if: typeof gulpIf;
  pug: typeof gulpPug;
  htmlPrettify: typeof gulpHtmlPrettify;
  sass: typeof gulpSass;
  stylus: typeof gulpStylus;
  postCss: typeof gulpPostCss;
  sourcemaps: typeof gulpSourcemaps;
}

下面的代码没有TypseScript编译错误，但是如果执行编译的TypeScript，会出现TypeError: gulpPlugins.postCss is not a function错误。

import * as gulp from 'gulp';
import * as GulpPlugins from 'gulp-load-plugins';

// I did not create types for this libary yet, so temporary make TypeScript to ignore it
// @ts-ignore
import * as postcssNormalizeWhitespace from 'postcss-normalize-whitespace';

gulpPlugins: IGulpPlugins = GulpPlugins();

return gulp.src(SOURCE_FILES_GLOB_SELECTION)
    .pipe(gulpPlugins.postCss([postcssNormalizeWhitespace]))
    .pipe(gulp.dest('build'));

如果要写

import * as gulp from 'gulp';
import * as GulpPlugins from 'gulp-load-plugins';

/* When I wrote this question, types in DefinitelyTyped for this library was not exists yet,
 * but I created it. However did not create the pull request yet.
 */
import * as gulpPostCss from 'gulp-postcss';

// I did not create types for this libary yet, so temporary make typescript ingore it
// @ts-ignore
import * as postcssNormalizeWhitespace from 'postcss-normalize-whitespace';


return gulp.src(SOURCE_FILES_GLOB_SELECTION)
    .pipe(gulpPostCss([postcssNormalizeWhitespace]))
    .pipe(gulp.dest('build'));

相反，JavaScript 将正常工作。

我看不懂，哪里弄错了。让我重复一遍，扩展 IGulpPlugins 中除 gulp-postcss 之外的所有插件都有效。

我写的gulp-postcss的类型是：

/// <reference types="node"/>
import Vinyl = require('vinyl');

declare function GulpPostCss(plugins?: Array<string>, options?: GulpPostCss.Options): NodeJS.ReadWriteStream;
declare function GulpPostCss(callback?: (file: Vinyl) => { plugins?: Array<string>, options?: GulpPostCss.Options }): NodeJS.ReadWriteStream;

declare namespace GulpPostCss {
    interface Options {
        parser?: string;
    }
}

export = GulpPostCss;

Answer 1

有 2 件事你没做对。

你打错了，或者可能不明白 gulp-load-plugins 是如何工作的。

如果您的插件名称是 gulp-post-css，那么它将变为 gulpPlugins.postCss。但是，该插件名称是 gulp-postcss，因此它将是：

gulpPlugins.postcss(...) // NOT gulpPlugins.postCss !!!

你不懂打字稿。

这与打字稿无关。

这是一条经验法则：typescript 对 javascript 运行时行为的影响为零。每当您发现运行时错误时，它一定来自 typescript 的 javascript 端。

虽然 1. 已经解决了你的问题，但我们假设你必须使用 gulpPlugins.postCss。为了让它起作用，请尝试添加这些行：

import * as gulpPostCss from 'gulp-postcss';
gulpPlugins.postCss = gulpPostCss;

现在可以使用了。

`gulp-postcss 不是函数` 由 gulp-load-plugins 提供时出现类型错误

`gulp-postcss is not a function` type error when it provided by gulp-load-plugins

javascript

node.js

typescript

gulp

postcss