source: frontend/node_modules/webpack/lib/UseStrictPlugin.js

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

"use strict";

const {
        JAVASCRIPT_MODULE_TYPE_AUTO,
        JAVASCRIPT_MODULE_TYPE_DYNAMIC,
        JAVASCRIPT_MODULE_TYPE_ESM
} = require("./ModuleTypeConstants");
const ConstDependency = require("./dependencies/ConstDependency");

/** @typedef {import("../declarations/WebpackOptions").JavascriptParserOptions} JavascriptParserOptions */
/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./Dependency").DependencyLocation} DependencyLocation */
/** @typedef {import("./Module").BuildInfo} BuildInfo */
/** @typedef {import("./javascript/JavascriptParser")} JavascriptParser */
/** @typedef {import("./javascript/JavascriptParser").Range} Range */

const PLUGIN_NAME = "UseStrictPlugin";

class UseStrictPlugin {
        /**
         * Applies the plugin by registering its hooks on the compiler.
         * @param {Compiler} compiler the compiler instance
         * @returns {void}
         */
        apply(compiler) {
                compiler.hooks.compilation.tap(
                        PLUGIN_NAME,
                        (compilation, { normalModuleFactory }) => {
                                /**
                                 * Handles the hook callback for this code path.
                                 * @param {JavascriptParser} parser the parser
                                 * @param {JavascriptParserOptions} parserOptions the javascript parser options
                                 */
                                const handler = (parser, parserOptions) => {
                                        parser.hooks.program.tap(PLUGIN_NAME, (ast) => {
                                                const firstNode = ast.body[0];
                                                if (
                                                        firstNode &&
                                                        firstNode.type === "ExpressionStatement" &&
                                                        firstNode.expression.type === "Literal" &&
                                                        firstNode.expression.value === "use strict"
                                                ) {
                                                        // Remove "use strict" expression. It will be added later by the renderer again.
                                                        // This is necessary in order to not break the strict mode when webpack prepends code.
                                                        // @see https://github.com/webpack/webpack/issues/1970
                                                        const dep = new ConstDependency(
                                                                "",
                                                                /** @type {Range} */ (firstNode.range)
                                                        );
                                                        dep.loc = /** @type {DependencyLocation} */ (firstNode.loc);
                                                        parser.state.module.addPresentationalDependency(dep);
                                                        /** @type {BuildInfo} */
                                                        (parser.state.module.buildInfo).strict = true;
                                                }
                                                if (parserOptions.overrideStrict) {
                                                        /** @type {BuildInfo} */
                                                        (parser.state.module.buildInfo).strict =
                                                                parserOptions.overrideStrict === "strict";
                                                }
                                        });
                                };

                                normalModuleFactory.hooks.parser
                                        .for(JAVASCRIPT_MODULE_TYPE_AUTO)
                                        .tap(PLUGIN_NAME, handler);
                                normalModuleFactory.hooks.parser
                                        .for(JAVASCRIPT_MODULE_TYPE_DYNAMIC)
                                        .tap(PLUGIN_NAME, handler);
                                normalModuleFactory.hooks.parser
                                        .for(JAVASCRIPT_MODULE_TYPE_ESM)
                                        .tap(PLUGIN_NAME, handler);
                        }
                );
        }
}

module.exports = UseStrictPlugin;