# Code compilation

# Compile JS code to ES5

With this option on, the developer tools will use babel to compile the JS code into ES5 standard code to meet the requirements of running on a lower version of the phone system.

After version 1.05.2106091 of the tool, the originalES6 to ES5andenhanced compilationsoptions are consolidated ascompiling the JS code into ES5, which is consistent with the originalenhanced compilationlogic.For older versions of the documentation, see here .

Function explaination:

• Based on the babel7 implementation, usingpreset-env,Supports the latestECMAScriptsyntax, compiled to{chrome: 53, ios: 8}
• Share Babel auxiliary functions, which are located by default in the project@ babel / runtimedirectory, via the project configuration file configuration
• Support async / await syntax, injectregeneratorRuntimeon demand, directory location consistent with auxiliary functions
• The first line of the file is/ / use strict disable;, you can disable the current file strict mode;Starting with version 1.05.2108172,setting.disableUseStrictin project.config.jsonWhentrue, strict mode can be disabled globally without having to deal with individual files separately.
• You can specify any file or directory without compilation (e.g. miniprogram_npm) through theproject configuration file
• The original logic supports thestage0syntax, and for forward compatibility, introduces a series of proposal plug-ins
• With regard to polyfill, a large number ofes6related polyfills can be referenced in the documentation under enhanced compilation, adding:Array.prototype.includes(es7)、Object.entries(es8)、Object.values(es8)

# Style Completion

When this option is turned on, the development tool automatically detects and corrects missing styles to ensure a normal display on lower-version systems.Although most of the problems can be circumvented, it is recommended that developers check the true performance of Weixin Mini Program separately on iOS and Android.

# Compression code

With this option on, developer tools will help developers compress and obfuscatejavascriptcode when uploading code, reducing the size of the package.

# Code Protection

When this option is turned on, the developer tool attempts to protect the project code, mainly by flattening the file and replacing the filenames referred to byrequire. This feature is not suitable for the following circumstances

1. For Weixin Mini Program only simple pages, turn on this function does not work well
2. A file larger than 500kb that usesrequireto refer to a file in a project may report that the file was not found at runtime
3. Dynamic reference cases such asvara = 'somefile.js'; require(a);
4. The case where therequirefunction to another variable, such asvar a = require; a('somefile.js');
5. The case whererequireas a parameter to a binary operator, e.g.require + 1;
6. Using the...operator and not turning on ES6 to ES5

# Enable multicore compilation

This option is visible on computers with four cores and above. Enabling this option will make full use of CPU resources to compile the project's JS code and improve the efficiency of compilation. You can choose to turn this off.

# Native support for compiling TypeScript

Tools improve support for typescript projects by compiling plug-ins.

Instead of having both ts files and js files in the Typescript project, the new template only needs to create ts files, and no need to generate js files with the same name. The new template does not need to execute the npm runtsc command before each compilation. In addition, the tool supports compiling less or sass files into wxss files.Please see Native Support for TypeScript