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callbacks.js
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81 lines (63 loc) · 1.81 KB
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const items = ['Pencil', 'Notebook', 'yo-yo', 'Gum', 'Pencil', 'Notebook', 'yo-yo', 'Gum'];
function firstItem(arr, cb) {
// firstItem passes the first item of the given array to the callback function.
cb(arr[0]);
}
firstItem(items, (firstItem) => {
console.log(firstItem);
})
function getLength(arr, cb) {
// getLength passes the length of the array into the callback.
cb(arr.length);
}
getLength(items, (length) => {
console.log(length);
})
function last(arr, cb) {
// last passes the last item of the array into the callback.
cb(arr[arr.length - 1]);
}
last(items, (theLast) => {
console.log(theLast);
})
function sumNums(x, y, cb) {
// sumNums adds two numbers (x, y) and passes the result to the callback.
cb(x + y);
}
sumNums(1, 2, (numSum) => {
console.log(numSum);
})
function multiplyNums(x, y, cb) {
// multiplyNums multiplies two numbers and passes the result to the callback.
cb(x * y);
}
multiplyNums(2, 3, (multi) => {
console.log(multi);
})
function contains(item, list, cb) {
// contains checks if an item is present inside of the given array/list.
// Pass true to the callback if it is, otherwise pass false.
for (let i = 0; i < list.length; i++) {
if (list[i] === item) {
cb(true);
}
}
cb(false);
}
contains('Gum', items, (contains) => {
console.log(contains);
})
/* STRETCH PROBLEM */
function removeDuplicates(array, cb) {
// removeDuplicates removes all duplicate values from the given array.
// Pass the duplicate free array to the callback function.
// Do not mutate the original array.
const unique = [];
for (let i = 0; i < array.length; i++) {
contains(array[i], unique, isUnique => isUnique ? undefined : unique.push(array[i]));
}
cb(unique);
}
removeDuplicates(items, (duplicatesRemoved) => {
console.log(duplicatesRemoved);
})