can now debug minified

Author: benholloway

lib/build/esmangleify.js

@@ -0,0 +1,83 @@
+'use strict';
+
+var codegen        = require('escodegen'),
+    esprima        = require('esprima'),
+    through        = require('through2'),
+    convert        = require('convert-source-map'),
+    sourceMapToAst = require('sourcemap-to-ast'),
+    esmangle       = require('esmangle'),
+    merge          = require('lodash.merge');
+
+/**
+ * Esprima based minifier transform for browserify
+ * @see http://sokra.github.io/source-map-visualization
+ */
+function esmangleify(opt) {
+
+  // options is the escodegen format
+  var format = merge({
+    renumber   : true,
+    hexadecimal: true,
+    escapeless : true,
+    compact    : true,
+    semicolons : false,
+    parentheses: false
+  }, opt);
+
+  // transform
+  return function browserifyTransform(file) {
+    var buffer = [];
+    return through(transfrom, flush);
+
+    function transfrom(data, encoding, done) {
+      /* jshint validthis:true */
+      buffer.push(data);
+      done();
+    }
+
+    function flush(done) {
+      /* jshint validthis:true */
+      var content = buffer.join('');
+
+      // parse code to AST using esprima
+      var ast;
+      try {
+        ast = esprima.parse(content, {
+          loc   : true,
+          source: file
+        });
+      } catch(e) {
+        return done(e);
+      }
+
+      // make sure the AST has the data from the original source map
+      var converter     = convert.fromSource(content);
+      var originalMap   = converter && converter.toObject();
+      var sourceContent = content;
+      if (originalMap) {
+        sourceMapToAst(ast, originalMap);
+        sourceContent = originalMap.sourcesContent[0];
+      }
+
+      // mangle the AST
+      var updated = esmangle.mangle(ast);
+
+      // generate compressed code from the AST
+      var pair = codegen.generate(updated, {
+        sourceMap        : true,
+        sourceMapWithCode: true,
+        format           : format
+      });
+
+      // ensure that the source map has sourcesContent or browserify will not work
+      pair.map.setSourceContent(file, sourceContent);
+      var mapComment = convert.fromJSON(pair.map.toString()).toComment();
+
+      // push to the output
+      this.push(new Buffer(pair.code + mapComment));
+      done();
+    }
+  };
+}
+
+module.exports = esmangleify;