Package Exports

jstransform
jstransform/src/docblock
jstransform/src/utils
jstransform/visitors/es6-arrow-function-visitors
jstransform/visitors/es6-arrow-function-visitors.js
jstransform/visitors/es6-class-visitors
jstransform/visitors/es6-destructuring-visitors
jstransform/visitors/es6-object-concise-method-visitors
jstransform/visitors/es6-object-short-notation-visitors
jstransform/visitors/es6-rest-param-visitors
jstransform/visitors/es6-template-visitors
jstransform/visitors/es7-spread-property-visitors

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (jstransform) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

JSTransform

A simple utility for pluggable JS syntax transforms using the esprima parser.

Makes it simple to write and plug-in syntax transformations
Makes it simple to coalesce multiple syntax transformations in a single pass of the AST
Gives complete control over the formatting of the output on a per-transformation basis
Supports source map generation
Comes pre-bundled with a small set of (optional) ES6 -> ES5 transforms

Examples

Using a pre-bundled or existing transform:

/**
 * Reads a source file that may (or may not) contain ES6 classes, transforms it
 * to ES5 compatible code using the pre-bundled ES6 class visitors, and prints 
 * out the result.
 */
var es6ClassVisitors = require('jstransform/visitors/es6-class-visitors').visitorList;
var fs = require('fs');
var jstransform = require('jstransform');

var originalFileContents = fs.readFileSync('path/to/original/file.js', 'utf-8');

var transformedFileData = jstransform.transform(
  es6ClassVisitors,
  originalFileContents
);

console.log(transformedFileData.code);

Using multiple pre-bundled or existing transforms at once:

/**
 * Reads a source file that may (or may not) contain ES6 classes *or* arrow
 * functions, transforms them to ES5 compatible code using the pre-bundled ES6 
 * visitors, and prints out the result.
 */
var es6ArrowFuncVisitors = require('jstransform/visitors/es6-arrow-function-visitors').visitorList;
var es6ClassVisitors = require('jstransform/visitors/es6-class-visitors').visitorList;
var jstransform = require('jstransform');

// Normally you'd read this from the filesystem, but I'll just use a string here
// to simplify the example.
var originalFileContents = "var a = (param1) => param1; class FooClass {}";

var transformedFileData = jstransform.transform(
  es6ClassVisitors.concat(es6ArrowFuncVisitors),
  originalFileContents
);

// var a = function(param1)  {return param1;}; function FooClass(){"use strict";}
console.log(transformedFileData.code);

Writing a simple custom transform:

/**
 * Creates a custom transformation visitor that prefixes all calls to the
 * `eval()` function with a call to `alert()` saying how much of a clown you are
 * for using eval.
 */
var jstransform = require('jstransform');
var Syntax = require('esprima-fb').Syntax;
var utils = require('jstransform/src/utils');

function visitEvalCallExpressions(traverse, node, path, state) {
  // Appends an alert() call to the output buffer *before* the visited node
  // (in this case the eval call) is appended to the output buffer
  utils.append('alert("...eval?...really?...");', state);

  // Now we copy the eval expression to the output buffer from the original
  // source
  utils.catchup(node.range[1], state);
}
visitEvalCallExpressions.test = function(node, path, state) {
  return node.type === Syntax.CallExpression
         && node.callee.type === Syntax.Identifier
         && node.callee.name === 'eval';
};

// Normally you'd read this from the filesystem, but I'll just use a string here
// to simplify the example.
var originalFileContents = "eval('foo');";

var transformedFileData = jstransform.transform(
  [visitEvalCallExpressions], // Multiple visitors may be applied at once, so an
                              // array is always expected for the first argument
  originalFileContents
);

// alert("...eval?...really?...");eval('foo');
console.log(transformedFileData.code);