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Browser

Run Prettier in the browser using its standalone version. This version doesn’t depend on Node.js. It only formats the code and has no support for config files, ignore files, CLI usage, or automatic loading of plugins.

The standalone version comes as:

  • ES modules: standalone.mjs, starting in version 3.0 (In version 2, esm/standalone.mjs.)
  • UMD: standalone.js, starting in version 1.13

The browser field in Prettier’s package.json points to standalone.js. That’s why you can just import or require the prettier module to access Prettier’s API, and your code can stay compatible with both Node and the browser as long as webpack or another bundler that supports the browser field is used. This is especially convenient for plugins.

prettier.format(code, options)

Required options:

  • parser (or filepath): One of these options has to be specified for Prettier to know which parser to use.

  • plugins: Unlike the format function from the Node.js-based API, this function doesn’t load plugins automatically. The plugins option is required because all the parsers included in the Prettier package come as plugins (for reasons of file size). These plugins are files in https://unpkg.com/browse/prettier@2.7.1/plugins/

    You need to load the ones that you’re going to use and pass them to prettier.format using the plugins option.

See below for examples.

Usage

Global

<script src="https://unpkg.com/prettier@2.7.1/standalone.js"></script>
<script src="https://unpkg.com/prettier@2.7.1/plugins/graphql.js"></script>
<script>
  (async () => {
    const formatted = await prettier.format("type Query { hello: String }", {
      parser: "graphql",
      plugins: prettierPlugins,
    });
  })();
</script>

Note that the unpkg field in Prettier’s package.json points to standalone.js, that’s why https://unpkg.com/prettier can also be used instead of https://unpkg.com/prettier/standalone.js.

ES Modules

<script type="module">
  import * as prettier from "https://unpkg.com/prettier@2.7.1/standalone.mjs";
  import pluginGraphql from "https://unpkg.com/prettier@2.7.1/plugins/graphql.mjs";

  const formatted = await prettier.format("type Query { hello: String }", {
    parser: "graphql",
    plugins: [pluginGraphql],
  });
</script>

AMD

define([
  "https://unpkg.com/prettier@2.7.1/standalone.js",
  "https://unpkg.com/prettier@2.7.1/plugins/graphql.js",
], async (prettier, ...plugins) => {
  const formatted = await prettier.format("type Query { hello: String }", {
    parser: "graphql",
    plugins,
  });
});

CommonJS

const prettier = require("prettier/standalone");
const plugins = [require("prettier/plugins/graphql")];
(async () => {
  const formatted = await prettier.format("type Query { hello: String }", {
    parser: "graphql",
    plugins,
  });
})();

This syntax doesn’t necessarily work in the browser, but it can be used when bundling the code with browserify, Rollup, webpack, or another bundler.

Worker

importScripts("https://unpkg.com/prettier@2.7.1/standalone.js");
importScripts("https://unpkg.com/prettier@2.7.1/plugins/graphql.js");
(async () => {
  const formatted = await prettier.format("type Query { hello: String }", {
    parser: "graphql",
    plugins: prettierPlugins,
  });
})();

Parser plugins for embedded code

If you want to format embedded code, you need to load related plugins too. For example:

<script type="module">
  import * as prettier from "https://unpkg.com/prettier@2.7.1/standalone.mjs";
  import pluginBabel from "https://unpkg.com/prettier@2.7.1/plugins/babel.mjs";

  console.log(
    await prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {
      parser: "babel",
      plugins: [pluginBabel],
    })
  );
  // Output: const html = /* HTML */ `<DIV> </DIV>`;
</script>

The HTML code embedded in JavaScript stays unformatted because the html parser hasn’t been loaded. Correct usage:

<script type="module">
  import * as prettier from "https://unpkg.com/prettier@2.7.1/standalone.mjs";
  import pluginBabel from "https://unpkg.com/prettier@2.7.1/plugins/babel.mjs";
  import pluginHtml from "https://unpkg.com/prettier@2.7.1/plugins/html.mjs";

  console.log(
    await prettier.format("const html=/* HTML */ `<DIV> </DIV>`", {
      parser: "babel",
      plugins: [pluginBabel, pluginHtml],
    })
  );
  // Output: const html = /* HTML */ `<div></div>`;
</script>
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