Iterators!!!
const formSteps = [
"CONTACT",
"EXPERIENCE",
"EDUCATION"
];What is an Iterator?
- In JavaScript an iterator is an object which defines a sequence and potentially a return value upon its termination. (From MDN Web Docs)
- An iterator is mechanism that allows you to get each item in a collection in order.
const myCollection = [1, 2, 3, 4, 5];const y = myCollection.forEach(n => n * 2);// => [2, 4, 6, 8, 10]// => undefinedconst x = myCollection.map(n => n * 2);How do Iterators work?
function createFunction(value) {
return function() {
return value;
}
}
const x = createFunction("some value");
const y = x();// ƒ () {
// return value;
// }// "some value"
function createIterator(collection) {
let index = 0;
return function() {
const result = collection[index];
index += 1;
return result;
}
}
const getNext = createIterator([1, 2, 3, 4, 5])
const value = getNext()Closure
Iterator Protocol
const iterator = createIterator([1, 2, 3, 4, 5]);
let result = iterator.next();
// { value: 1, done: false }
while (!result.done) {
console.log(result.value);
result = it.next();
}Iterators
By Becca Nelson
