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Arrays can be treated as string-indexable types #17191
Description
Activity
You can think of it this way - for the purposes of indexing,
numberis a subtype ofstringdue to how JavaScript worksRyan Cavanaugh (@RyanCavanaugh) - could this be addressed in strict-mode?
In strict mode, not all JS is a valid TS (e.g. no implicit any), therefore this presents an opportunity to discourage
const foo = {'42': 'foo'}; const bar = foo[42]in favour of stricter typings.Alternatively I would be interested in in other approaches or workarounds given that assigning an array to what is expected to be an object could have significant issues at run-time.
Arrays are objects.
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on Jun 14, 2018
TypeScript Version: 2.4.0
Code
Expected behavior:
The code above doesn't compile.
Actual behavior:
Typescript silently accepts such code.