In my JS code I have two booleans, flag1 and flag2. I want to create an array ['a', 'b', 'c'] where a is included only if flag1 is true, and where b is included only if flag2 is true. What I have now is [flag1 ? 'a' : null, 'b', flag2 ? 'c' : null], but if flag1 and flag2 are false this gives me [null, 'b', null] instead of ['b'].
SOLUTION:
Here's the cleanest way I found for doing it: [...(flag1 ? ['a'] : []),'b',...(flag2 ? ['c'] : [])]
You could take a function which returns either the value inside an array or an empty array for spreading into an array.
const
either = (condition, value) => condition ? [value] : [],
getArray = (flag1, flag2) => [
...either(flag1, 'a'),
...either(flag2, 'b'),
'c'
];
console.log(...getArray(true, true));
console.log(...getArray(false, true));
console.log(...getArray(true, false));
console.log(...getArray(false, false));
Another one implementation:
const flag1 = true;
const flag2 = false;
const data = [[flag1, 'a'], [flag2, 'b'], [true, 'c']];
const result = data.flatMap(([flag, letter]) => flag ? letter : []);
console.log(result);