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

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.