The escodegen npm package is a code generator that takes an Abstract Syntax Tree (AST) and converts it back into JavaScript code. It is commonly used in the process of developing compilers, code transformers, and other tools that manipulate code structure programmatically.

What are escodegen's main functionalities?

Generating code from an AST

This feature allows you to generate JavaScript code from an AST. The provided code sample demonstrates generating a simple expression '40 + 2' from its AST representation.

const escodegen = require('escodegen');
const ast = {
  type: 'BinaryExpression',
  operator: '+',
  left: { type: 'Literal', value: 40 },
  right: { type: 'Literal', value: 2 }
};
const code = escodegen.generate(ast);
console.log(code); // '40 + 2'

Generating source maps

escodegen can also generate source maps alongside the generated code, which is useful for debugging purposes. The code sample shows how to generate both code and a source map from an AST.

const escodegen = require('escodegen');
const ast = { /* ... */ };
const codeWithSourceMap = escodegen.generate(ast, { sourceMap: true, sourceMapWithCode: true });
console.log(codeWithSourceMap.code); // Generated code
console.log(codeWithSourceMap.map.toString()); // Source map

Custom code generation

You can customize the formatting of the generated code by specifying options such as indentation and newline characters. The code sample illustrates how to generate code with custom formatting options.

const escodegen = require('escodegen');
const ast = { /* ... */ };
const customCode = escodegen.generate(ast, {
  format: {
    indent: {
      style: '  ',
      base: 0
    },
    newline: '\n'
  }
});
console.log(customCode); // Custom formatted code

Other packages similar to escodegen

Readme

Source

Escodegen (escodegen) is ECMAScript (also popularly known as JavaScript) code generator from Parser API AST. See online generator demo.

Install

Escodegen can be used in a web browser:

<script src="escodegen.browser.js"></script>

or in a Node.js application via the package manager:

npm install escodegen

Usage

A simple example: the program

escodegen.generate({
    type: 'BinaryExpression',
    operator: '+',
    left: { type: 'Literal', value: 40 },
    right: { type: 'Literal', value: 2 }
});

produces the string '40 + 2'

See the API page for options. To run the tests, execute npm test in the root directory.

License

Escodegen

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

source-map

SourceNodeMocks has a limited interface of mozilla/source-map SourceNode implementations.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the names of the Mozilla Foundation nor the names of project contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Status

FAQs

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Last updated on 14 Jun 2013

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