Calculating sums
JavaScript
Read fire tipSplitting arrays into X elements and “the rest”
JavaScript
This little helper can split arrays into the first X elements and “the rest”. You could use it to show the first five photos from a list and a link that says “27 more photos”.
// takes an array and the number of elements to extract from the start
const spliceHead = (array, sizeOfHead) => {
// create a copy, because `.splice()` changes the array in place
const copy = [...array]
// cut the first `sizeOfHead` elements from the array and store them
const head = copy.splice(0, sizeOfHead)
// return TWO arrays: the first `sizeOfHead` elements and “the rest”
return [head, copy]
}
// this can split an array into “the first three, and everything else”
spliceHead(['John', 'Paul', 'George', 'Ringo'], 3)
// ⇒ [ ['John', 'Paul', 'George'], ['Ringo'] ]
// we can assign the results to two variables with destructuring
const [head, rest] = spliceHead(['Bibidi', 'Babidi', 'Boo'], 2)
console.log(`${head[0]}, ${head[1]}, and ${rest.length} more`)
// ⇒ 'Bibidi, Babidi, and 1 more'