[Golang] Online Concatenate and Compress JavaScript Files

March 07, 2016

Concatenate and compress JavaScript files via Golang and online Google Closure Compiler.

package main

import (
      "io/ioutil"
      "net/http"
      "net/url"
      "path"
)

func minjs(baseDir string, jsFiles []string, outputPath string) {
      var jsCode []byte
      for _, file := range jsFiles {
              jsPath := path.Join(baseDir, file)
              println("concatenating " + jsPath + " ...")
              b, err := ioutil.ReadFile(jsPath)
              if err != nil {
                      panic(err)
              }
              jsCode = append(jsCode, b...)
      }

      params := url.Values{}
      //params.Set("code_url", "https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_core.js")
      //params.Set("code_url", "https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_ps2t.js")
      //params.Set("code_url", "https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_pt2s.js")
      //params.Set("code_url", "https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_s2t.js")
      //params.Set("code_url", "https://github.com/twnanda/twnanda/raw/master/theme/javascript/tongwen_table_t2s.js")
      params.Set("js_code", string(jsCode))
      params.Set("compilation_level", "SIMPLE_OPTIMIZATIONS")
      params.Set("language", "ECMASCRIPT5")
      params.Set("output_format", "text")
      params.Set("output_info", "compiled_code")

      println("\nCompressing combined js online ...")
      resp, err := http.PostForm("https://closure-compiler.appspot.com/compile", params)
      if err != nil {
              panic(err)
      }
      defer resp.Body.Close()
      b, err := ioutil.ReadAll(resp.Body)
      if err != nil {
              panic(err)
      }
      ioutil.WriteFile(path.Join(baseDir, outputPath), b, 0644)
}

func main() {
      baseDir := "dictionary"
      jsFiles := []string{
              "common/app/scripts/services/data/dicBooks.js",
              "common/app/scripts/services/data/succinctTrie.js",
              "common/app/scripts/services/data/i18nStrings.js",
              "app/scripts/app.js",
              "app/scripts/controllers.js",
              "app/scripts/directives/inputSuggest.js",
              "app/scripts/directives/draggableAndEvents.js",
              "common/app/scripts/services/paliWordJson.js",
              "common/app/scripts/services/shortExp.js",
              "common/app/scripts/services/ngBits.js",
              "common/app/scripts/services/wordSearch.js",
              "common/app/scripts/directives/dropdown.js",
              "common/app/scripts/filters/expOrder.js",
              "common/app/scripts/i18n.js",
      }
      minjs(baseDir, jsFiles, "app/all_compiled.js")
}