Typescript array initialization

Question

here I define the variable results to be an array of strings:

let results: string[];

and here below, I assign a value to kick things off:

results['searchCaption'] = "";

and then, the show stops with ERROR TypeError: Cannot set property 'searchCaption' of undefined

What am I missing here? Do I need to define an interface for it first?

Did you initialize the array? IE: let results: string[] = []? It would appear from the error that results is undefined, indicating that you never assigned anything to it. — CRice
– CRice, Commented Dec 18, 2017 at 21:35
string[] only defines what type the variable is. It doesn't assign anything to it. — JJJ
– JJJ, Commented Dec 18, 2017 at 21:36
results['searchCaption'] = ""; is not a valid array syntax. Arrays are index based - objects are key based. — tymeJV
– tymeJV, Commented Dec 18, 2017 at 21:37
Perfect pointer! Sure that is it. All along, I was thinking that let results: string[]; would kicks things off with results = [] anyway! I think in ASP, it was not the case, my memory mislead me. Thank you! CRice! — Average Joe
– Average Joe, Commented Dec 18, 2017 at 21:37
Happy to help, but per @tymeJV's comment, you're assigning things to the array as though it were an object, which while possible, is definitely an anti-pattern. — CRice
– CRice, Commented Dec 18, 2017 at 21:39

David Anthony Acosta · Accepted Answer · 2017-12-18 21:58:45Z

9

What you want is this:

let results = new Array<string>();
results['searchCaption'] = '';

answered Dec 18, 2017 at 21:58

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1 Comment

I will accept the answer though there seems to be an anti-pattern about the use of arrays this way I came to know.