Improve code quality and write tests

node_modules/core-js-compat/index.js

@@ -0,0 +1,105 @@
+'use strict';
+const { coerce, lt, lte } = require('semver');
+const browserslist = require('browserslist');
+const data = require('./data');
+const getModulesListForTargetVersion = require('./get-modules-list-for-target-version');
+const has = Function.call.bind({}.hasOwnProperty);
+
+const mapping = new Map([
+  ['ios_saf', 'ios'],
+  ['and_chr', 'chrome'],
+  ['and_ff', 'firefox'],
+]);
+
+const validTargets = new Set([
+  'android',
+  'chrome',
+  'edge',
+  'electron',
+  'firefox',
+  'ie',
+  'ios',
+  'node',
+  'opera',
+  'phantom',
+  'safari',
+  'samsung',
+]);
+
+function coercedLte(a, b) {
+  return lte(coerce(a), coerce(b));
+}
+
+function coercedLt(a, b) {
+  return lt(coerce(a), coerce(b));
+}
+
+function normalizeBrowsersList(list) {
+  return list.map(it => {
+    let [engine, version] = it.split(' ');
+    if (mapping.has(engine)) engine = mapping.get(engine);
+    else if (engine === 'android' && !coercedLte(version, '4.4.4')) engine = 'chrome';
+    return [engine, version];
+  }).filter(([engine]) => validTargets.has(engine));
+}
+
+function reduceByMinVersion(list) {
+  const targets = new Map();
+  for (const [engine, version] of list) {
+    if (!targets.has(engine) || coercedLte(version, targets.get(engine))) {
+      targets.set(engine, version);
+    }
+  }
+  return targets;
+}
+
+function checkModule(name, targets) {
+  if (!has(data, name)) throw new TypeError(`Incorrect module: ${ name }`);
+  const requirements = data[name];
+  const result = {
+    required: false,
+    targets: {},
+  };
+  for (const [engine, version] of targets) {
+    if (!has(requirements, engine) || coercedLt(version, requirements[engine])) {
+      result.required = true;
+      result.targets[engine] = version;
+    }
+  }
+  return result;
+}
+
+function compat({ targets, filter, version }) {
+  const list = browserslist(targets);
+  const engines = normalizeBrowsersList(list);
+  const reducedTargets = reduceByMinVersion(engines);
+
+  const result = {
+    list: [],
+    targets: {},
+  };
+
+  let modules = Array.isArray(filter) ? filter : Object.keys(data);
+
+  if (filter instanceof RegExp) modules = modules.filter(it => filter.test(it));
+  else if (typeof filter == 'string') modules = modules.filter(it => it.startsWith(filter));
+
+  if (version) {
+    const availableModules = new Set(getModulesListForTargetVersion(version));
+    modules = modules.filter(name => availableModules.has(name));
+  }
+
+  modules.forEach(key => {
+    const check = checkModule(key, reducedTargets);
+    if (check.required) {
+      result.list.push(key);
+      result.targets[key] = check.targets;
+    }
+  });
+
+  return result;
+}
+
+module.exports = compat;
+module.exports.compat = compat;
+module.exports.getModulesListForTargetVersion = getModulesListForTargetVersion;