Dispatching on a Value with switch in JavaScript

Especially when looping, a program often needs to “update” a binding to hold a value based on that binding’s previous value.

counter = counter + 1;

JavaScript provides a shortcut for this.

counter += 1;

Similar shortcuts work for many other operators, such as result *= 2 to double result or counter -= 1 to count downward.

This allows us to shorten our counting example a little more.

for (let number = 0;

number <= 12;

number += 2) {



For counter += 1 and counter -= 1, there are even shorter equivalents: counter++ and counter-.

Source: Haverbeke Marijn (2018), Eloquent JavaScript: A Modern Introduction to Programming,

No Starch Press; 3rd edition.

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