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How to change the final array to the front in JavaScript?

Time:05-15

The case is:

function trocaPrimeiroEUltimo(array) {
    array.array[0]
    array.array[array.length - 1]
    return array
}

I did this way, but it didn't work. I can't change the structure of the function, just what it's inside. Someone, could please help me?

CodePudding user response:

Do you want to replace the last value with the first value? if so, do:

temp = array[0]

array[0] = array[array.length-1]

array[array.length-1] = temp

That's a simple swap.

CodePudding user response:

The syntax makes use of new ES6 capabilities (destructuring an array). This way the exchange can be done without a temporary variable.

The whole thing can even be done as a one-liner:

const arr=[7,8,9,10,11];

const swapFirstLast=(a,l)=>([a[0],a[l]]=[a[l=a.length-1],a[0]],a);

console.log(swapFirstLast(arr))

The use of the argument l is also something you probably would not do in a "real" application. I only went for it so I would not have to define the variable locally. l is assigned a value on the right hand side of the assignment expression. By the time the result needs to be stored l has been calculated and can also be used for addressing the right target element.

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