Merge pull request #1351 from mathjax/feature/hasown-polyfill

Provide hasOwn polyfill configuration option.

Author: dpvc

components/mjs/startup/hasown.js

@@ -0,0 +1,10 @@
+import {MathJax} from '#js/components/global.js';
+
+if (!Object.hasOwn && MathJax.config.startup.polyfillHasOwn) {
+  Object.hasOwn = function (el, prop) {
+    if (typeof el === 'undefined' || el === null) {
+      throw new TypeError('Cannot convert undefined or null to object');
+    }
+    return Object.prototype.hasOwnProperty.call(Object(el), prop);
+  }
+}

components/mjs/startup/init.js

@@ -1,3 +1,4 @@
+import './hasown.js'; // Can be removed with ES2024 implementation of Object.hasown
 import './lib/startup.js';
 
 import {combineDefaults} from '#js/components/global.js';

ts/components/startup.ts

@@ -620,6 +620,7 @@ if (typeof MathJax._.startup === 'undefined') {
     typeset: true,
     ready: Startup.defaultReady.bind(Startup),
     pageReady: Startup.defaultPageReady.bind(Startup),
+    polyfillHasOwn: true, // Can be removed with ES2024 implementation of Object.hasown
   });
   combineWithMathJax({
     startup: Startup,