nolanlawson/optimize-js

walk.js aborts with error if input contains ES6 code

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#3 opened on Sep 19, 2016

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 (8 comments) (0 reactions) (0 assignees)JavaScript (3,761 stars) (128 forks)batch import
bughelp wanted

Description

Perhaps because walk.js does not support ES6?

Example: start.js.txt

TypeError: types[type] is not a function
    at walk (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/walk.js:17:16)
    at Object.skip (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/types.js:293:3)
    at walk (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/walk.js:17:16)
    at Object.exports.BinaryExpression.exports.LogicalExpression.exports.AssignmentExpression (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/types.js:243:3)
    at walk (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/walk.js:17:16)
    at Object.skip (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/types.js:293:3)
    at walk (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/walk.js:17:16)
    at Object.exports.ExpressionStatement (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/types.js:32:3)
    at walk (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/walk.js:17:16)
    at Object.skip (/usr/local/lib/node_modules/optimize-js/node_modules/walk-ast/lib/types.js:293:3)

Contributor guide

Tech stack
javascriptnodejs
Domain
clitooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
JavaScriptAST traversalES6 syntax
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Investigate the walk ast library, specifically walk.js and types.js, to identify which ES6 node types are not handled. The error 'types[type] is not a function' suggests that the type map in types.js lacks entries for ES6 syntax like arrow functions, classes, etc. Look at the skip function and the walk function to understand how node types are resolved. Consider adding ES6 node types or updating the parser to support them.