build-browser-features.js

"use strict";
/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
Object.defineProperty(exports, "__esModule", { value: true });
const browserslist = require("browserslist");
const caniuse_lite_1 = require("caniuse-lite");
const ts = require("typescript");
class BuildBrowserFeatures {
    constructor(projectRoot, scriptTarget) {
        this.projectRoot = projectRoot;
        this.scriptTarget = scriptTarget;
        this.supportedBrowsers = browserslist(undefined, { path: this.projectRoot });
        this._es6TargetOrLater = this.scriptTarget > ts.ScriptTarget.ES5;
    }
    /**
     * True, when one or more browsers requires ES5
     * support and the scirpt target is ES2015 or greater.
     */
    isDifferentialLoadingNeeded() {
        return this._es6TargetOrLater && this.isEs5SupportNeeded();
    }
    /**
     * True, when one or more browsers requires ES5 support
     */
    isEs5SupportNeeded() {
        return !this.isFeatureSupported('es6-module');
    }
    /**
     * True, when a browser feature is supported partially or fully.
     */
    isFeatureSupported(featureId) {
        // y: feature is fully available
        // n: feature is unavailable
        // a: feature is partially supported
        // x: feature is prefixed
        const criteria = [
            'y',
            'a',
        ];
        const data = caniuse_lite_1.feature(caniuse_lite_1.features[featureId]);
        return !this.supportedBrowsers
            .some(browser => {
            const [agentId, version] = browser.split(' ');
            const browserData = data.stats[agentId];
            const featureStatus = (browserData && browserData[version]);
            // We are only interested in the first character
            // Ex: when 'a #4 #5', we only need to check for 'a'
            // as for such cases we should polyfill these features as needed
            return !featureStatus || !criteria.includes(featureStatus.charAt(0));
        });
    }
}
exports.BuildBrowserFeatures = BuildBrowserFeatures;