Type guard check if the given value is undefined.
The value to check
True if the value is undefined, otherwise false
const data = ['demo', undefined, 'demo'];const count = data.filter(isUndef).length; // 1 Copy
const data = ['demo', undefined, 'demo'];const count = data.filter(isUndef).length; // 1
v0.4.0
Type guard check if the given value is undefined.