Unknown expression type `ThisExpression`

[ljharb]

on v1.0.1:

TYPES[expression.type] is not a function
TypeError: TYPES[expression.type] is not a function
    at extract ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/expressions/index.js:102:32)
    at Object.extractValueFromMemberExpression [as MemberExpression] ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/expressions/MemberExpression.js:23:30)
    at extract ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/expressions/index.js:102:32)
    at Object.extractValueFromMemberExpression [as MemberExpression] ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/expressions/MemberExpression.js:23:30)
    at Object.extract [as JSXExpressionContainer] ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/expressions/index.js:102:32)
    at getValue ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/values/index.js:52:27)
    at extractValue ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/getAttributeValue.js:24:12)
    at getAttributeValue ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/util/getAttributeValue.js:41:10)
    at EventEmitter.JSXOpeningElement ($PWD/node_modules/eslint-plugin-jsx-a11y/lib/rules/img-has-alt.js:56:54)
    at emitOne (events.js:82:20)
    at EventEmitter.emit (events.js:169:7)

I added a console.log to line 101 in index.js and got:

Node {
  type: 'ThisExpression',
  start: 1419,
  end: 1423,
  loc: 
   SourceLocation {
     start: Position { line: 54, column: 17 },
     end: Position { line: 54, column: 21 } },
  range: [ 1419, 1423 ] }

Perhaps the comment "This will map correctly for *all* possible expression types." above the function is inaccurate, and it should be explicitly handling unknown expression types?

[beefancohen]

Yeah, it should be more fault tolerant than that 😦

Mind sharing the JSX that was used so I can add a handler for a ThisExpression

[ljharb]

I have no idea - I ran it on our huge codebase and it doesn't tell me which file it's looking at :-/

[beefancohen]

Ah, that's okay, I've created a function to handle ThisExpression. I'm actually not sure if the code should be more defensive because it could return false positives. In your experience would it be better for the code to fail so user can report a bug or fail gracefully even if it incorrectly warns?

[ljharb]

I'd say it'd be better for it to fail with a meaningful error message.

[beefancohen]

as in an actual throw new Error(``Encountered an unknown type '${type}' while trying to get the prop ${prop}'s value. Please file an issue on Github to get this resolved immediately.``) ??

[ljharb]

sure, perhaps with the filename and line number

[ljharb]

@evcohen not to put too much pressure on you, but this is blocking release of v8 of eslint-config-airbnb ;-) is it something you hope to get out soon?

[beefancohen]

ah working on it now, sorry about that. will let you know when im about to publish.

[beefancohen]

actually, let me just get a fix out for ThisExpression and then add error handling for next release. might take some time to figure out how to get propagate certain values to that function to give a meaningful error message.

[beefancohen]

Just published v1.0.2 let me know if you face any other issues. I'm going to work on better error handling right now for every rule.

[ljharb]

Thanks!