Angular 4 app using IE 11, "Can't execute code from a freed script"

Question

I have an Angular app which I think is version 4. IE 11 crashes during a login sequence in this app: "Can't execute code from a freed script". According to the IE console the error happens in the polyfills bundle at line 10939 ("var testString = delegate.toString()"), which looks like this:

  var checkIEAndCrossContext = function (nativeDelegate, delegate, target, args) {
    if (!isDisableIECheck && ieOrEdge) {
        if (isEnableCrossContextCheck) {
            try {
                var testString = delegate.toString();
                if ((testString === FUNCTION_WRAPPER || testString == BROWSER_TOOLS)) {
                    nativeDelegate.apply(target, args);
                    return false;
                }
            }
            catch (error) {
                nativeDelegate.apply(target, args);
                return false;
            }
        }
        else {
            var testString = delegate.toString();   // <===== HERE!
            if ((testString === FUNCTION_WRAPPER || testString == BROWSER_TOOLS)) {
                nativeDelegate.apply(target, args);
                return false;
            }
        }
    }
    else if (isEnableCrossContextCheck) {
        try {
            delegate.toString();
        }
        catch (error) {
            nativeDelegate.apply(target, args);
            return false;
        }
    }
    return true;
};

I think that is from this line in the polyfills file:

 /* Zone JS is required by Angular itself.*/
 import 'zone.js/dist/zone';  // Included with Angular CLI.

This is from "package.json" regarding zone.js:

"zone.js": "^0.8.4"

The polyfill.ts file:

/**
 * This file includes polyfills needed by Angular and is loaded before the app.
 * You can add your own extra polyfills to this file.
 *
 * This file is divided into 2 sections:
 *   1. Browser polyfills. These are applied before loading ZoneJS and are sorted by browsers.
 *   2. Application imports. Files imported after ZoneJS that should be loaded before your main
 *      file.
 *
 * The current setup is for so-called "evergreen" browsers; the last versions of browsers that
 * automatically update themselves. This includes Safari >= 10, Chrome >= 55 (including Opera),
 * Edge >= 13 on the desktop, and iOS 10 and Chrome on mobile.
 *
 * Learn more in https://angular.io/docs/ts/latest/guide/browser-support.html
 */

/***************************************************************************************************
 * BROWSER POLYFILLS
 */

/** IE9, IE10 and IE11 requires all of the following polyfills. **/
import 'core-js/es6/symbol';
import 'core-js/es6/object';
import 'core-js/es6/function';
import 'core-js/es6/parse-int';
import 'core-js/es6/parse-float';
import 'core-js/es6/number';
import 'core-js/es6/math';
import 'core-js/es6/string';
import 'core-js/es6/date';
import 'core-js/es6/array';
import 'core-js/es6/regexp';
import 'core-js/es6/map';
import 'core-js/es6/weak-map';
import 'core-js/es6/set';

/** IE10 and IE11 requires the following for NgClass support on SVG elements */
 import 'classlist.js';  // Run `npm install --save classlist.js`.

/** IE10 and IE11 requires the following to support `@angular/animation`. */
 import 'web-animations-js';  // Run `npm install --save web-animations-js`.


/** Evergreen browsers require these. **/
import 'core-js/es6/reflect';
import 'core-js/es7/reflect';


/** ALL Firefox browsers require the following to support `@angular/animation`. **/
 import 'web-animations-js';  // Run `npm install --save web-animations-js`.



/***************************************************************************************************
 * Zone JS is required by Angular itself.
 */
import 'zone.js/dist/zone';  // Included with Angular CLI.



/***************************************************************************************************
 * APPLICATION IMPORTS
 */

/**
 * Date, currency, decimal and percent pipes.
 * Needed for: All but Chrome, Firefox, Edge, IE11 and Safari 10
 */
// import 'intl';  // Run `npm install --save intl`.
/**
 * Need to import at least one locale-data with intl.
 */
// import 'intl/locale-data/jsonp/en';

import 'hammerjs/hammer';

What would you recommend that i do in this case?

Answer 1

One solution is to set the variable isEnableCrossContextCheck to true, so that IE should run the code containing a try/catch block, which can handle the error.

        if (isEnableCrossContextCheck) {
            try {
                var testString = delegate.toString();
                if ((testString === FUNCTION_WRAPPER || testString == BROWSER_TOOLS)) {
                    nativeDelegate.apply(target, args);
                    return false;
                }
            }
            catch (error) {
                nativeDelegate.apply(target, args);
                return false;
            }
        }
        else {
            var testString = delegate.toString(); 
            if ((testString === FUNCTION_WRAPPER || testString == BROWSER_TOOLS)) {
                nativeDelegate.apply(target, args);
                return false;
            }
        }

This post shows how to to that:

Angular 4 put a global constant available to zone.js

Answer 2

Simply use the below code to resolve the zone.js errors in IE 11/EDGE versions. The following code has to be placed in the polyfills.ts :

if (document['documentMode'] || /Edge/.test(navigator.userAgent)) {
    (window as any).__Zone_enable_cross_context_check = true;
}

Make the config changes in above code based on your requirement

Answer 3

According to this thread the actual fix is to do nothing! This error only occurs when DevTools are open in IE, which basically means it only happens when you are looking for it. IE is just wonderful, isn't it?

Closing DevTools (as almost everyone will when viewing a website) will not cause this error to happen.

The above fixes can be applied for a testing or a development environment if needed, but ideally do not apply them to a production environment since it just adds some extra overhead that isn't needed.