# ast-eval > Statically evaluate AST Latest version **0.8.0** (published 2015-03-03) · Unlicensed license · 0 weekly downloads ## Install ```sh npm install ast-eval pnpm add ast-eval yarn add ast-eval bun add ast-eval ``` ## 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 | 0.8.0 | | Published | 2015-03-03 | | First published | 2015-02-12 | | Weekly downloads | 0 | | License | Unlicensed | | TypeScript types | none | | Module format | CommonJS | | Dependencies | 13 | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 11 | | Author | Deema Ywanov | | Maintainers | dfcreative | | Keywords | static-eval, ecmascript, esprima, ast, es-trim, estrim, espurify, ast-eval, static, static-analysis, estools, eval, es-eval, eseval, preeval, pre-eval, fold, constants, compiler, optimizing, dataflow, data-flow, analysis | ## Links - npm: https://www.npmjs.com/package/ast-eval - Repository: http://github.com/dfcreative/ast-eval - Homepage: https://github.com/dfcreative/ast-eval - Issues: https://github.com/dfcreative/ast-eval/issues - npm.io page: https://npm.io/package/ast-eval ## Dependencies (13) - [clone](https://npm.io/package/clone.md) ^1.0.0 - [xtend](https://npm.io/package/xtend.md) ^4.0.0 - [escope](https://npm.io/package/escope.md) ^2.0.4 - [esprima](https://npm.io/package/esprima.md) ^2.0.0 - [esquery](https://npm.io/package/esquery.md) ^0.3.0 - [ast-test](https://npm.io/package/ast-test.md) ^1.1.1 - [tosource](https://npm.io/package/tosource.md) ^0.1.3 - [ast-types](https://npm.io/package/ast-types.md) ^0.6.12 - [escodegen](https://npm.io/package/escodegen.md) ^1.6.1 - [is-object](https://npm.io/package/is-object.md) ~1.0.1 - [ast-replace](https://npm.io/package/ast-replace.md) ^1.1.3 - [is-primitive](https://npm.io/package/is-primitive.md) ^1.0.0 - [ast-redeclare](https://npm.io/package/ast-redeclare.md) ^1.0.4 ## 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 - 0.8.0 (latest) — 2015-03-03 - 0.7.1 — 2015-02-14 - 0.7.0 — 2015-02-14 - 0.6.5 — 2015-02-13 - 0.6.4 — 2015-02-13 - 0.6.3 — 2015-02-13 - 0.6.2 — 2015-02-13 - 0.6.1 — 2015-02-13 - 0.6.0 — 2015-02-13 - 0.5.0 — 2015-02-13 - 0.4.2 — 2015-02-13 - 0.4.1 — 2015-02-13 - 0.4.0 — 2015-02-13 - 0.3.0 — 2015-02-13 - 0.2.0 — 2015-02-13 - … 1 more at https://npm.io/package/ast-eval/versions ## README # ast-eval [![Build Status](https://travis-ci.org/dfcreative/ast-eval.svg?branch=master)](https://travis-ci.org/dfcreative/ast-eval) [![experimental](http://badges.github.io/stability-badges/dist/experimental.svg)](http://github.com/badges/stability-badges) Statically evaluate expressions in AST, also known as [constants folding](http://en.wikipedia.org/wiki/Constant_folding). Useful for precompilation tasks. ## Use ```sh npm install --save ast-eval ``` ```js var esprima = require('esprima'); var gen = require('escodegen').generate; var astEval = require('ast-eval'); var ast = esprima.parse('[1, 2 === "2", 3+4*10, [2] === 2]'); ast = astEval(ast); gen(ast); //'[1, false, 43, false]' ``` ## API ### preeval(Node, options) → Node Evaluate expressions in a Node, return a new Node with optimized shorten expression nodes. ## Features * [x] Fold expressions * [x] Binary expressions: `1000 * 60 * 60` → `36e6` * [x] Logical expressions: `{a:1} && {b:2}` → `true` * [x] Math expressions: `Math.sin(Math.Pi / 2 )` → `1` * [x] Fold arrays * [x] Safe methods: `[1,2,3,new Date].concat(4, [5], new Date)` → `[1,2,3,new Date,4,5, new Date]` * [x] Unsafe methods: `[1,2,3].map(function(x){ return x*2})` → `[2,4,6]` * [ ] Static methods: `Array.from([1, 2, 3], function(x){ return x*2; })` → `[2,4,6]` * [ ] Prototype methods: `Array.prototype.slice.call([1,2,3], 1,2)` → `[2]` * [ ] Fold static globals (what’s that?) * [x] Decompute object access (optionally) * [x] `a['x'] = 1` → `a.x = 1` * [x] Fold strings * [x] `'a b c'.split(' ')` → `['a', 'b', 'c']` * [ ] [Propagate constants](http://en.wikipedia.org/wiki/Constant_folding#Constant_propagation) * [ ] Simple flow analysis: `var x = 1; x + 2;` → `3;` * [ ] Scope analysis * [ ] Method substitution: `var slice = Array.prototype.slice; var x = [1,2,3]; var y = slice(x)'` * [ ] Fold loops * [ ] `var x = []; for (var i = 0; i < 10; i++) {x[i] = 10*i;}` * [ ] Fold proxy functions * [ ] Remove unused props * [ ] Undead code * [ ] Empty isolated functions * [ ] Remove unused variables (after enabling constants) * [ ] Remove unused functions * [ ] Remove unused properties * [ ] Fold clone-code * `a.x`×3 → `var _a = a; _a.x` * [ ] Data-flow analysis * [ ] Precall functions * [ ] Substitute variables * [ ] Provide exports * [ ] Fold primitives * [ ] new Array([1,2,3,...]) * [ ] [1,2,3,...] * [ ] Rearrange things * [ ] Hoist functions (place after first use) * [ ] Fold variable declarations ## References * [List of compiler optimizations](http://en.wikipedia.org/wiki/Optimizing_compiler) — ideas of folding. * Substack’s [static-eval](https://github.com/substack/static-eval) — evaluate static expressions. * [esmangle](https://github.com/estools/esmangle) [![NPM](https://nodei.co/npm/ast-eval.png?downloads=true&downloadRank=true&stars=true)](https://nodei.co/npm/ast-eval/) --- _Source: https://npm.io/package/ast-eval · Machine-readable twin of the npm.io package page. 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