JS Small Tricks for Problem Solving 1 - Iterating

Iteration in Array, Set, Map

Iterating through an array with an index is straightforward. You can use the ES6 forEach() method:

arr.forEach((item, index) => { ... });

However, when you need to return a value immediately while iterating over an object, breaking out of the parent function is not easy.

In such cases, if you are willing to accept a small trade-off in time and space complexity, Object.entries() is a good option. Once you have the entries, you can iterate with a simple for...of loop.

for (let [index, value] of iterable) {
  console.log(index, value)
}

Map and Set are also commonly used in problem-solving to reduce time complexity.

For this reason, being comfortable with for...in and for...of when iterating over objects is essential.

→ Related docs: Difference between ( for... in ) and ( for... of ) statements?

In Practice

For example, suppose you want to collect all unique numbers from an array and then iterate over them. Just put all the numbers into a Set and iterate with for...of. That's all there is to it!