How to fix TypeScript error: expression of type can't be used to index type All In One
errors
Element implicitly has an 'any' type, because expression of type '' can't be used to index type ''.
solutions
type guards
// const txt = foo["txt"]
let txt;
// ✅
if('txt' in foo) {
txt = foo["txt"]
}
keyof
// const txt = foo["txt"]
// ✅
const txt = foo["txt" as keyof FooBar]
keyof+typeof
// const txt = foo["txt"]
// ✅
type KT = keyof typeof foo;
const txt = foo["txt" as KT]
demos
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Narrowing
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#typeof-type-guards
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#instanceof-narrowing
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#control-flow-analysis
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates
https://www.typescriptlang.org/docs/handbook/2/classes.html#this-based-type-guards
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#conditional-type-constraints
cheatsheets
https://www.typescriptlang.org/cheatsheets
refs
https://bobbyhadz.com/blog/typescript-element-implicitly-has-any-type-expression
https://www.totaltypescript.com/concepts/type-string-cannot-be-used-to-index-type
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