webpack/lib/JsonGenerator.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
"use strict";

const { ConcatSource, RawSource } = require("webpack-sources");

const stringifySafe = data => {
	const stringified = JSON.stringify(data);
	if (!stringified) {
		return undefined; // Invalid JSON
	}

	return stringified.replace(/\u2028|\u2029/g, str =>
		str === "\u2029" ? "\\u2029" : "\\u2028"
	); // invalid in JavaScript but valid JSON
};

class JsonGenerator {
	generate(module, dependencyTemplates, runtimeTemplate) {
		const source = new ConcatSource();
		const data = module.buildInfo.jsonData;
		if (data === undefined) {
			return new RawSource(
				runtimeTemplate.missingModuleStatement({
					request: module.rawRequest
				})
			);
		}
		let finalJson;
		if (
			Array.isArray(module.buildMeta.providedExports) &&
			!module.isUsed("default")
		) {
			// Only some exports are used: We can optimize here, by only generating a part of the JSON
			const reducedJson = {};
			for (const exportName of module.buildMeta.providedExports) {
				if (exportName === "default") continue;
				const used = module.isUsed(exportName);
				if (used) {
					reducedJson[used] = data[exportName];
				}
			}
			finalJson = reducedJson;
		} else {
			finalJson = data;
		}
		// Use JSON because JSON.parse() is much faster than JavaScript evaluation
		const jsonSource = JSON.stringify(stringifySafe(finalJson));
		const jsonExpr = `JSON.parse(${jsonSource})`;
		source.add(`${module.moduleArgument}.exports = ${jsonExpr};`);
		return source;
	}
}

module.exports = JsonGenerator;