---
sourceDocument: Yokohama Build or modify applications
sourceDocumentLink: https://servicenow-prod.fluidtopics.net/r/yokohama/application-development

 Release :

    - yokohama

ft:locale :

    - en-US

ft:publication_title :

    - Yokohama Build or modify applications

ft:clusterId :

    - cadev

bundleId :

    - cadev

workflow :

    - Development, Data, and Analytics


---

# Set the JavaScript mode for an application

# Set the JavaScript mode for an application {#ariaid-title1}

* Release version: Yokohama
* 
* Updated January 30, 2025
* 
* ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 1 minute to read

Configure which ECMAScript features can be used in an application by selecting the JavaScript mode.

## Before you begin

Role required: delegated developer role granting full access or admin

## About this task

The JavaScript mode is a design and runtime setting for custom applications and scripts. To support existing server-side scripts and new scripts developed to the ECMAScript 2021 standard, the JavaScript engine has three
modes: ECMAScript 2021 (ES12), ES5 Standards, and Compatibility. For more information about each mode, see [JavaScript modes](https://www.servicenow.com/docs/access?context=c_JS_modes&version=yokohama&pubname=yokohama-api-reference&ft:locale=en-US).

For applications that use ES5 Standards or Compatibility mode, you can also turn on ECMAScript 2021 (ES12) for individual scripts in the application. For more information, see [Turn on ECMAScript 2021 (ES12) mode for a script](https://www.servicenow.com/docs/access?context=set-es12-mode-scripts&version=yokohama&pubname=yokohama-api-reference&ft:locale=en-US).  
Note:  
Switching the JavaScript mode to ECMAScript 2021 (ES12) for an existing application might change the behavior of its scripts. For more information, see [Considerations for switching JavaScript modes](https://www.servicenow.com/docs/access?context=considerations-switching-javascript-mode&version=yokohama&pubname=yokohama-api-reference&ft:locale=en-US).

## Procedure

1. In the application navigator, enter <kbd class="ph userinput">sys_app.list</kbd>.
2. Select an application.
3. In the JavaScript Mode field, select the mode to use.
   * ECMAScript 2021 (ES12): Supports a subset of ECMAScript 2021 (ES12) and ECMAScript 2022 (ES13) syntax and features.
   * ES5 Standards Mode: Supports ECMAScript5 syntax and features.
   * Compatibility Mode: Used for all scripts developed prior to the addition of ES5 Standards mode.
   {#set-javascript-mode-application__choices_xvq_f4b_hbc}
4. Select Update.
**Related tasks**   

* [Modify an app's settings in ServiceNow Studio](https://servicenow-prod.fluidtopics.net/TQMgCWgaqDDz__XbfYicVQ "Adjust an app's settings in ServiceNow Studio using the full platform app record in app settings. Change the name, description, or other metadata associated with the app, and view all related links associated to the application.")