如何从gruntfile中的另一个文件获取变量

Question

I am new to grunt .

My requirement is that I need to uglify my files based on the variable set on another file.

Let's say I have some abc.js file in which I have a variable var is_uglify = true;

I need to read the value of the variable in gruntfile and perform the build accordingly.

If variable is true , I need to do:

grunt.registerTask('build', ['clean:build','uglify']);

otherwise

grunt.registerTask('build', ['clean:build']);

Can anyone help with this?

Answer 1

This can be achieved by:

1. Defining a Custom Task - namely getValue in the gist below.

2. In the getValue Task/Function utilize grunt.file.read to obtain the contents of abc.js .

3. Then use a regex to match the Boolean value assigned to the variable is_uglify .

4. Once the Boolean value for is_uglify is obtained then conditionally run either the registered Task named buildA or buildB using grunt.task.run

---

Gruntfile.js

The following gist shows how this can be achieved:

module.exports = function (grunt) {

  'use strict';

  grunt.initConfig({
    uglify: {
      // ... <-- Define as necessary.
    },
    clean: {
      build: {
        //...  <-- Define as necessary.
      }
    }
  });

  grunt.registerTask('getValue', 'Gets the value of a variable', function () {
    var filepath = "path/to/abc.js", // <-- Define as necessary.
      content = grunt.file.read(filepath),
      value = content.match(/(?:var is_uglify = )(true|false);/);

    if (!value) {
      grunt.fail.warn(
        '\'var is_uglify = [true|false];\' not found in: ' + filepath['yellow']
      )
    }

    if (value[1] === 'true') {
      grunt.task.run(['buildA']);
    } else {
      grunt.task.run(['buildB']);
    }
  });

  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks('grunt-contrib-clean');

  grunt.registerTask('build', ["getValue"]);
  grunt.registerTask('buildA', ['clean:build','uglify']);
  grunt.registerTask('buildB', ['clean:build']);
};

---

Additional Notes

• In the following line of code the "path/to/abc.js" part will need to be redefined as per your directory structure. This must be the path to your file containing var is_uglify = ...; :

     var filepath = "path/to/abc.js",

• An explanation to the regex pattern /(?:var is_uglify = )(true|false);/ can be found here . It will find the first match only in abc.js .

• The getValue Task/Function will warn if the is_uglify variable is missing and the Task/function simply fails and returns early.

• After you have defined the configuration for the uglify and clean:build Task run $ grunt build via your CLI.