JavaScript Set explained

remove-duplicates-from-array.js

// Embedded in https://twitter.com/meduzen/status/1369679118992871428

// OMG, lot of duplicated entries!
const stepsNames = [
    "step-basic",
    "step-basic",
    "step-basic",
    "step-specification",
    "step-specification",
    "step-specification",
    "step-specification",
    "step-specification",
    "step-title-description",
    "step-contact-information",
    "step-pricing",
    "step-payment",
    "step-confirmation"
]

// Let’s remove them in two steps!

// 1. With a Set, we can have a collection of unique values:

let uniqueStepsNames = new Set(stepsNames)

// Duplicates are now gone, but Set is an object, not an array:

// { 0: "step-basic", 1: "step-specification"… }

// 2. Using the spread syntax, we turn the object into an array.

uniqueStepsNames = [...uniqueStepsNames]

// This 👆 can be read:
// “Creates an ARRAY [] that will receive ALL INNER VALUES OF ...uniqueStepsNames.”

// `uniqueStepsNames` is now an array:
// ["step-basic", "step-specification"…]

// Or, alternatively, in 1 step instead of 2:
const uniqueStepsNames = [...new Set(stepsNames)]