I'm interested in utilizing tuples as return types in array.map(..) without the need to declare their types in advance, particularly for my concise functions that typically yield tuples with just two elements.
How can I accurately specify the return type of an anonymous function?
// sample input
let words: string[] = [ "apple", "banana" ]
// potential type definition
type Pair = [string, number];
// detailed function declaration
function wordLength(word: string): Pair
{
return [word, word.length];
}
// various approaches using .map()
// yielding the same outcome for syntax variation
let result0 = words.map( w => wordLength(w) );
let result1 = words.map( (w: string): Pair => wordLength(w) );
let result2 = words.map( (w: string): Pair =>
{
return [w, w.length]
});
let result3 = words.map( (w: string): [string, number] =>
{
return [w, w.length]
});
let result4 = words.map( (w): [string, number] =>
{
return [w, w.length]
});
let result5 = words.map( (w): [string, number] => [w, w.length] );
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