# astronaut > A library for transforming Esprima/SpiderMonkey ASTs. Latest version **0.1.4** (published 2014-05-09) · BSD-2-Clause license · 0 weekly downloads ## Install ```sh npm install astronaut pnpm add astronaut yarn add astronaut bun add astronaut ``` ## Health **Score 15/100 (F)** — status: abandoned. Positive: no vulnerabilities. Warnings: low downloads; no types; no esm support; pre 1.0. Negative: abandoned; low maintenance score. ## Facts | | | |---|---| | Version | 0.1.4 | | Published | 2014-05-09 | | First published | 2014-05-03 | | Weekly downloads | 0 | | License | BSD-2-Clause | | TypeScript types | none | | Module format | CommonJS | | Dependencies | 4 | | Known vulnerabilities | 0 (+2 in 1 direct dependencies) | | Install scripts | no | | GitHub stars | 4 | | Author | Giovanni Fernandez-Kincade | | Maintainers | giokincade | | Keywords | ast, abstract syntax tree, astronaut, esprima, spidermonkey | ## Links - npm: https://www.npmjs.com/package/astronaut - Repository: https://github.com/giokincade/astronaut - Issues: https://github.com/giokincade/astronaut/issues - npm.io page: https://npm.io/package/astronaut ## Dependencies (4) - [esprima](https://npm.io/package/esprima.md) ~1.2.0 - [nodeunit](https://npm.io/package/nodeunit.md) ~0.8.7 - [escodegen](https://npm.io/package/escodegen.md) ~1.3.2 - [underscore](https://npm.io/package/underscore.md) ~1.6.0 ## Alternatives - [update-check](https://npm.io/package/update-check.md) — 4.0M weekly downloads - [react-native-onesignal](https://npm.io/package/react-native-onesignal.md) — 134.5K weekly downloads - [react-redux-toastr](https://npm.io/package/react-redux-toastr.md) — 33.7K weekly downloads - [@nocobase/plugin-notification-manager](https://npm.io/package/@nocobase/plugin-notification-manager.md) — 2.0K weekly downloads - [react-simple-toasts](https://npm.io/package/react-simple-toasts.md) — 1.9K weekly downloads ## Recent versions - 0.1.4 (latest) — 2014-05-09 - 0.1.3 — 2014-05-06 - 0.1.2 — 2014-05-05 - 0.1.0 — 2014-05-04 - 0.0.0 — 2014-05-03 ## README # Astronaut Astronaut is a library for traversing and manipulating the javascript AST. [![Build Status](https://travis-ci.org/giokincade/astronaut.svg?branch=master)](https://travis-ci.org/giokincade/astronaut) # Examples Let's replace all instances of 5 with 4: ``` astronaut('1 + 5') .walk(function(node) { if (node.isLiteral() && node.value() === 5) { node.value(4); } }) .deparse() //'1 + 4' ``` Let's replace all instances of 5 with a call to the function "f": ``` astronaut('1 + 5') .walk(function(node) { if (node.isLiteral() && node.value() === 5) { node.replace('f()'); } }) .deparse() //'1 + f()' ``` Or how about we wrap them in a call to the function f: ``` astronaut('1 + 5') .walk(function(node) { if (node.isLiteral() && node.value() === 5) { node.wrap('f(<%= node %>)'); } }) .deparse() //'1 + f(5)' ``` Let's prefix all calls to f where the second argument is an array expression with a call to g and the same array: ``` var code = "f(); f(1, [1,2,3]);"; astronaut(code).walk(function(node) { if (node.isCallExpression() && node.calleeName() === "f" && node.arguments().length > 1 && node.arguments()[1].isArrayExpression()) { node.prefix("g(" + node.arguments()[1].deparse() + ')'); } }).deparse() //"f();g([1,2,3]);f(1,[1,2,3]);", ``` Let's wrap a function body in a try/catch: ``` var code = "function f(a) { return a; }"; astronaut(code).walk(function(node) { if (node.isBlockStatement() && node.parent.isFunctionDeclaration()) { node.wrap("try { <%= node %> } catch(e) {} }"); } }).deparse() //"function f(a) { try { return a; } catch(e) {} }"; ``` # Api ## astronaut ``` var astronaut = require('astronaut') ``` Astronaut takes a string to be parsed (using Esprima), or an already-parsed Esprima/SpiderMonkey AST, and returns an AstNode. ## AstNode ### AstNode.data The SpiderMonkey AST data for this node, with sub-nodes wrapped in AstNodes. Updates to this mutate the tree, but for non-primitive values it's recommended to use the replace/wrap functions. ### AstNode.parent A pointer to the parent of this node ### AstNode.parentKey The key in the parent that points to this node. ### AstNode.parentArrayIndex If parent[key] is an array, the index of this node in that array. This enables affix functions. ### AstNode.is <NodeType>() Returns a boolean indicating whether or note the node is of the specified type. ### AstNode.ast() Returns the SpiderMonkey AST for this node. ### AstNode.walk(callback) Walk the AST starting at this node, calling the callback along the way. ### AstNode.map(callback) Walk the tree, replacing nodes with new nodes produced by callback(node). To avoid thrashing the tree, if the callback returns null/undefined, no replacement occurs. ### AstNode.reduce(accumulator, callback) Reduce the tree down to a single value. `callback` should be a function that expects the accumulator as the first argument, the current node as the second, and returns the new accumulator. ### AstNode.deparse(options) A shortcut for escodegen.generate(AstNode.ast(), options) ### AstNode.wrap(codeOrTemplate) Wrap the current node in the code specified by an underscore template. The template can be a string to be parsed or a compiled template. The current node should be represented as `node` in the template. For example: node.wrap("f(<%= node =>)") ### AstNode.replace(code) Replace the current node with the results of parsing the input `code` ### AstNode.prefix(code) Insert the statement specified in code prior to the statement encoded by the current node. ### AstNode.suffix(code) Insert the statement specified in code after the statement encoded by the current node. # Installation ``` npm install astronaut ``` # Acknowledgements I was inspired by [burrito](https://github.com/substack/node-burrito), but was dissapointed by the lack of child pointers and wanted something that supported the Esprima AST. [Falafel](https://github.com/substack/node-falafel) seems like it may have solved both problems. --- _Source: https://npm.io/package/astronaut · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._