Ext JS Sencha Docs

Inside The App Build Process

The build script provided by Sencha Cmd is the component that ties together and automates the many low-level features of Sencha Cmd (such as the Compiler). There is rarely a one-size-fits-all solution for builds so the build script provides many options to configure and customize its behavior. This guide will explain the principles behind the build script and where you might look should you need to tailor the build process to suit your needs.


The following guides are recommended reading before proceeding further:


Internally, the sencha app build command does basic validation and calls in to the Apache Ant build script found in "build.xml" at the root of the application. Specifically, it calls the "build" target of this script. This means the entire build process can be examined, extended and (if necessary) even modified.

Because sencha app build simply invokes the "build" target of the Ant "build.xml" file, you can equivalently invoke a build directly from Ant. This can be useful in IDE's like Eclipse and NetBeans for invoking your builds but also in a Continuous Integration server that understands Ant (which is just about all of them).

The generated "build.xml" is a minimal Ant script that uses an Ant import task to import ".sencha/app/build-impl.xml" as well as several other files. While "build.xml" is intended to be edited after it is generated, the ".sencha/app/*-impl.xml" files are not. These files will be replaced bysencha app upgrade` and so should be edited unless absolutely necessary. These files are, however, an excellent reference but should be modified unless necessary.

Build Targets

The targets below define the application build process from start to finish. With the exception of init each target has a property that can be set to 1 to disable that step.

  • init
  • refresh
  • resolve (defaults to 1; set skip.resolve=0 to enable)
  • js
  • resources
  • sass
  • slice
  • page
  • native-package

With the exception of init each of these targets can be dropped out of the default build by use of a build property (see below) with the target name prefixed by "skip.". For example, to disable the slice target:


These steps can also be run individually if only that piece is desired. This is often the useful for rebuilding only the Sass:

sencha ant sass

Note: Using sencha ant is equivalent to using your own version of Ant if you have Ant 1.8 or higher installed.


Most aspects of the build script behind sencha app build are controlled by properties as is typical of Ant. In this case there are two kinds of properties: configuration properties and build properties.

Configuration Properties

Sencha Cmd configuration properties are available to the build script but also drive many other features of Sencha Cmd (like the compiler). To see the current set of configuration properties, run this command:

sencha diag show

In most cases you can tell where each property comes from by its prefix:

  • app. -- See "app.json" and ".sencha/app/sencha.cfg".
  • workspace. -- See "workspace.json" and ".sencha/workspace/sencha.cfg".
  • framework. -- See "cmd/sencha.cfg" in the Ext JS or Sencha Touch SDK.
  • cmd. -- See "sencha.cfg" in the Sencha Cmd install folder.

The use of configuration properties is much broader than the build process and is discussed in some detail in Advanced Sencha Cmd.

Build Properties

The build script defines many other properties that are specific to builds. These build properties are typically prefixed by "build.".

To see the current values of these you can run this command from your app folder:

sencha ant .props

Setting Build Properties

There are many ways to configure build properties. The simplest way is to edit one of the build properties files. To decide which file to edit it is helpful to know the priority of each of these files and under what conditions they are loaded.

  • "local.properties" -- If present, this file is loaded first. This file is intended to be applied only locally (to the local machine). It should not be committed to source control to be used by others. These settings take priority over any properties defined in other properties files as well as the current configuration properties.
  • Sencha Cmd configuration properties
  • ".sencha/app/${build.environment}.properties" -- Based on the value of the build.environment properties, exactly one of the following will be loaded. Setting properties in these files allow you to have different values for properties based on the type of build being run.
    • ".sencha/app/native.properties"
    • ".sencha/app/package.properties"
    • ".sencha/app/production.properties"
    • ".sencha/app/testing.properties"
  • ".sencha/app/build.properties" -- These properties are loaded next and have lower priority over the build-environment-specific properties. These are properties that are used by all (or most) environments. This file is intended for customization.
  • ".sencha/app/defaults.properties" -- These properties are the last (default) values to load. This file is "owned" by Sencha Cmd and will be updated each release as new properties are added. This file serves as a reference for the defined set of build properties but should not be edited; edit any of the other files instead.

The only properties that have higher priority than "local.properties" are those passed in via the command line.


Many common needs are accounted for via build properties, but it is impossible to account for all use cases in this way. When configuration options cannot accomplish the task, the next level of customization is to extend the generated "build.xml" Ant script.

In addition to the import task, "build.xml" contains a comment block describing many of the available extension points. These are in the form of optional Ant targets and are named after their build process step but with prefixes of "-before-" and "-after-". The most common extensions point then are these:

  • init
    • -before-init
    • -after-init
  • refresh
    • -before-refresh
    • -after-refresh
  • resolve
    • -before-resolve
    • -after-resolve
  • js
    • -before-js
    • -after-js
  • resources
    • -before-resources
    • -after-resources
  • sass
    • -before-sass
    • -after-sass
  • slice
    • -before-slice
    • -after-slice
  • page
    • -before-page
    • -after-page
  • native-package
    • -before-native-package
    • -after-native-package

To perform additional processing before or after any build step, add an appropriately named target to "build.xml". These targets will be invoked by sencha app build. These will also be invoked if you use Ant to directly invoke a particular target.

One common use of these extensions points is to post-process the build output in the "all-classes.js" file. Using a few predefined Ant tasks we can, for example, put a copyright header on the generated file after it is generated:

<target name="-after-page">
        <format property="THISYEAR" pattern="yyyy"/>

    The build.classes.file property holds the full path to the "all-classes.js"
    file so we use that variable rather than hard-code the name.
    <move file="${build.classes.file}" tofile="${build.classes.file}.tmp"/>

    <concat destfile="${build.classes.file}">
        <header filtering="no" trimleading="yes">
 * Copyright (C) ${THISYEAR}. All Rights Reserved.
 * My Company Name
        <fileset file="${build.classes.file}.tmp"/>

    <delete file="${build.classes.file}.tmp" />

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