Console Learner — An interactive JavaScript course.

5.5 Idioms

var obj = { text: 'ok'};

obj.missing || 'default'
As previously mentioned, boolean logic is commonly used to provide default values. The ?? nullish coalescing operator (introduced with ES11 in 2020) is a recent alternative in many cases.
obj && obj.text
It is also common to use boolean logic to avoid issues with possible null references. The ?. optional chaining operator (introduced with ES11 in 2020) simplifies this further.
obj && print(obj);

A third way of using boolean conditions is the cond && operation idiom. This code style avoids an if statement for short operations.
[0, 1, true, false, '', ' ', null, undefined].filter(Boolean)
[1, true, " "]
The built-in Boolean function coerces any value into a boolean. This is useful when filtering out null or empty values from an array. But note that 0 and false are also removed.
new Array(4).fill(0).map(Math.random).map(v => v * 10).map(Math.floor).join('-')
Some objects, such as Array, have methods that either return a new instance or a reference to itself. This makes it possible to use method chaining to avoid intermediate result variables.

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