All values in JavaScript when converted into a Boolean will return true unless they are one of the seven falsy primitives (false, null, undefined, 0n, 0, "", and NaN), in which case they will return false.
To cast a value to a Boolean, we can simply pass the value to the Boolean constructor, invoking it as a function:
Boolean(0); // => falseBoolean(1); // => true
The language will coerce values to Booleans when the values exist in a Boolean context. Here are some examples of such contexts (each marked with HERE):
- if ( HERE ) {...}
- do {...} while (HERE)
- while (HERE) {...}
- for (...; HERE; ...) {...}
- [...].filter(function() { return HERE })
- [...].some(function() { return HERE })
This list is not exhaustive. There ...
