@ilukanets/gulp-to-jst/index.js

> A [gulp](http://gulpjs.com/) plugin to compile [underscore](http://underscorejs.org/#template) / [lodash](http://lodash.com/docs#template) templates into a single file.

'use strict';

const pluginName = 'gulp-to-jst';
const Vinyl = require('vinyl');
const PluginError = require('plugin-error');
const through = require('through');
const assign = require('lodash/assign');
const template = require('lodash/template');

function pluginError(message) {
  return new PluginError(pluginName, message);
}

function getNamespace(namespace) {
  let currentPath = 'this';

  if (namespace !== 'this') {
    namespace
        .split('.')
        .forEach(function (part, index) {
          if (part !== 'this') {
            currentPath += '[' + JSON.stringify(part) + ']';
          }
        });
  }

  return currentPath;
}

const defaults = {
  amd: false,
  prettify: false,
  namespace: 'JST',
  processName: function (fileName) {
    return fileName;
  },
  processContent: function (source) {
    return source;
  },
  separator: '\n',
  templateSettings: {}
};

module.exports = function toJST(fileName, settings) {
  if (!fileName) {
    pluginError('Missing fileName.');
  }

  const options = assign({}, defaults, settings || {});
  const files = [];
  let namespace = '';

  function compile(file) {
    const name = options.processName(file.path);
    let contents = template(file.contents.toString(),
        options.templateSettings).source;

    if (options.prettify) {
      contents = contents.replace(/\n/g, '');
    }

    if (options.amd && !options.namespace) {
      return 'return '.concat(contents);
    }

    if (options.namespace) {
      namespace = getNamespace(options.namespace);
    }

    return namespace.concat('[', JSON.stringify(name),
        '] = ', contents, ';');
  }

  function write(file) {
    if (file.isNull()) {
      return;
    }

    if (file.isStream()) {
      return this.emit('error', pluginError('Streaming is not supporting.'));
    }

    if (file.isBuffer()) {
      files.push(file);
    }
  }

  function end() {
    const compiled = files.map(compile);

    if (options.amd) {
      if (options.prettify) {
        compiled.forEach(function (line, index) {
          compiled[index] = '  '.concat(line);
        });
      }
      compiled.unshift('define(function(){');
      if (!options.namespace) {
        compiled.push('  return '.concat(getNamespace(options.namespace), ';'));
      }
      compiled.push('});');
    }

    this.queue(new Vinyl({
      path: fileName,
      contents: Buffer.from(compiled.join(options.separator))
    }));

    this.queue(null);
  }

  return through(write, end);
}