Question

JavaScript

Write a function called "first" that takes in two arguments - the first is an argument called arr that is an array of numbers, the second is an optional number argument called num(hint: you'll need a default value - look back at the slides).

If "num" was not passed in (since it's optional), the "first" function will return an array containing the first item of the array.

If a value for "num" was given, the "first" function will return an array containing the first "num" values of the array.

See the example output below.

console.log(first([7, 9, 0, -2])); // [7]
console.log(first([], 3)); // [undefined, undefined, undefined]
console.log(first([7, 9, 0, -2], 3)); // [7, 9, 0]
console.log(first([7, 9, 0, -2], 6)); // [7, 9, 0, -2, undefined, undefined]

Answer 1

function first(arr,num=-1){

let out=[];

if(arr.length==0){

for(let i=0;i<num;i++){

out.push(undefined)

}

return out;

}else if(num==-1){

return arr[0];

}else if(num<=arr.length){

for(let i=0;i<num;i++){

out.push(arr[i]);

}return out

}else if(num>arr.length){

for(let i=0;i<num;i++){

if(i<arr.length){

out.push(arr[i]);

}else{

out.push(undefined);

}

}

return out;

}

}

console.log(first([7, 9, 0, -2]));

console.log(first([], 3));

console.log(first([7, 9, 0, -2], 3));

console.log(first([7, 9, 0, -2], 6));