Question 265822 in Javascript Question posted in
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Javascript – Get string value or first element of array as string

Have the following function:

function x(p: string | string[]): string | string[];

How do I ensure that the following just outputs a single string value?

console.log(x());

I.e.:

console.log(x("Hello")); // should be "Hello"
console.log(x(["Hello", "World"])); // should be "Hello"

Any shortcut in JavaScript?

Tags:

2

Answers


  1. 0

    like this:

    function x(p:string|string[]){
 return Array.isArray(p)?p[0]:p
}
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  2. 0

    You can use the fact that concat promotes scalars to arrays, and leaves arrays as is:

    function x(a) {
    return [].concat(a)[0]
}

console.log(x("Hello")); // should be "Hello"
console.log(x(["Hello", "World"])); // should be "Hello"

    That is, if you’re actually looking for a "shortcut", and not a technically correct solution, which would be not having such a function in the first place.

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