wiring.js

// wiring.js
// Exposes convenience methods for wiring up markup with scripts,
// stylesheets and other types of dependencies.

var util = require('util'),
    cheerio = require('cheerio'),
    fs = require('fs'),
    path = require('path');

var wiring = module.exports;

// Update a file containing HTML markup with new content, either
// appending, prepending or replacing content matching a particular
// selector
//
// - html     - a string containing HTML markup
// - tagName  - a valid CSS selector
// - content  - the inline content to update your selector with
// - mode     - a(ppend), p(repend), r(eplace), d(elete)
//
wiring.domUpdate = function domUpdate(html, tagName, content, mode){

  var $ = cheerio.load( html );

  if(content !== undefined) {
    if(mode === 'a') {
      // append
      $(tagName).append(content);
    } else if(mode === 'p') {
      // prepend
      $(tagName).prepend(content);
    } else if(mode === 'r') {
      // replace
      $(tagName).html(content);
    } else if(mode === 'd') {
      $(tagName).remove();
    }
    return $.html();
  } else {
    console.error('Please supply valid content to be updated.');
  }

};


// Insert specific content as the last child of each element matched
// by the tagName selector. Returns a string.
wiring.append = function append(html, tagName, content){
  return this.domUpdate(html, tagName, content, 'a');
};

// Insert specific content as the first child of each element matched
// by the tagName selector. Returns a string.
wiring.prepend = function prepend(html, tagName, content){
  return this.domUpdate(html, tagName, content, 'p');
};

// Insert specific content as the last child of each element matched
// by the tagName selector. Writes to file.
wiring.appendToFile = function appendToFile(path, tagName, content){
  var html = this.readFileAsString(path);
  var updatedContent = this.append(html, tagName, content);
  this.writeFileFromString(path, updatedContent);
};

// Insert specific content as the first child of each element matched
// by the tagName selector. Writes to file.
wiring.prependToFile = function prependToFile(path, tagName, content){
  var html = this.readFileAsString(path);
  var updatedContent = this.prepend(html, tagName, content);
  this.writeFileFromString(path, updatedContent);
};

// Generate a usemin-handler block.
//
// - blockType      - js, css
// - optimizedPath  - the final file to build
// - filesBlock     - a string containing populated script/style tags ready to be
//                    injected into a usemin block.
//
// Returns the new block.
wiring.generateBlock = function generateBlock(blockType, optimizedPath, filesBlock){
  var blockStart = "\n    <!-- build:" + blockType + " " + optimizedPath +" -->\n";
  var blockEnd = "    <!-- endbuild -->\n";
  return blockStart + filesBlock + blockEnd;
};

// Append files, specifying the optimized path and generating the necessary
// usemin blocks to be used for the build process.
//
// - fileType       - js (appends to the end of 'body'), css (appends to the
//                    end of 'head')
// - optimizedPath  - the final file to build
// - sourceFileList - the list of files to be appended. We check against the
//                    fileType to ensure the correct tags are wrapped around
//                    them and the right usemin blocks generated.
// - attrs          - A Hash of html attributes to generate along the generated
//                    script / link tags
//
// Returns updated content.
wiring.appendFiles = function appendFiles(html, fileType, optimizedPath, sourceFileList, attrs) {
  var files = "", blocks, updatedContent;

  attrs = this.attributes(attrs);

  if(fileType === "js") {
    sourceFileList.forEach(function(n) {
        files += ('    <script ' + attrs + ' src="' + n + '"></script>\n');
    });
    blocks = this.generateBlock('js', optimizedPath, files);
    updatedContent = this.append(html, 'body', blocks);
  } else if(fileType === "css") {
    sourceFileList.forEach(function(n) {
        files += ('    <link ' + attrs + ' rel="stylesheet" href="' + n  + '">\n');
    });
    blocks = this.generateBlock('css', optimizedPath, files);
    updatedContent = this.append(html, 'head', blocks);
  }

  return updatedContent;
};


// Computes a given Hash object of attributes into its HTML representation
//
// - attrs  - Hash object of attributes to generate
//
// Returns the generated string of attributes.
wiring.attributes = function attributes(attrs) {
  attrs = attrs || {};
  return Object.keys(attrs).map(function(key) {
    return key + '="' + attrs[key] + '"';
  }).join(' ');
};

// Scripts alias to appendFiles
wiring.appendScripts = function appendScripts(html, optimizedPath, sourceFileList, attrs) {
  return this.appendFiles(html, 'js', optimizedPath, sourceFileList, attrs);
};

// Simple script removal
wiring.removeScript = function removeScript(html, scriptPath) {
  return this.domUpdate(html, 'script[src$="' + scriptPath + '"]' , '', 'd');
};

wiring.appendStyles = function appendStyles(html, optimizedPath, sourceFileList, attrs) {
  return this.appendFiles(html, 'css', optimizedPath, sourceFileList, attrs);
};

wiring.removeStyle = function removeStyle( html, path ) {
  return this.domUpdate( html, 'link[href$="' + path + '"]' , '', 'd' );
};

// Append a directory of scripts
wiring.appendScriptsDir = function appendScriptsDir(html, optimizedPath, sourceScriptDir, attrs) {
  var sourceScriptList = fs.readdirSync(path.resolve(sourceScriptDir));
  return this.appendFiles(html, 'js', optimizedPath, sourceScriptList, attrs);
};

// Append a directory of stylesheets
wiring.appendStylesDir = function appendStylesDir(html, optimizedPath, sourceStyleDir, attrs) {
  var sourceStyleList = fs.readdirSync(path.resolve(sourceStyleDir));
  return this.appendFiles(html, 'css', optimizedPath, sourceStyleList, attrs);
};

wiring.readFileAsString = function readFileAsString(filePath) {
  return fs.readFileSync(path.resolve(filePath), 'utf8');
};

wiring.writeFileFromString = function writeFileFromString(html, filePath) {
   fs.writeFileSync(path.resolve(filePath), html, 'utf8');
};