You can consider using a very small, dependency-free library like Not. Solves all problems:
// at the basic level it supports primitives
let number = 10
let array = []
not('number', 10) // returns false
not('number', []) // throws error
// so you need to define your own:
let not = Object.create(Not)
not.defineType({
primitive: 'number',
type: 'integer',
pass: function(candidate) {
// pre-ECMA6
return candidate.toFixed(0) === candidate.toString()
// ECMA6
return Number.isInteger(candidate)
}
})
not.not('integer', 4.4) // gives error message
not.is('integer', 4.4) // returns false
not.is('integer', 8) // returns true
If you make it a habit, your code will be much stronger. Typescript solves part of the problem but doesn't work at runtime, which is also important.
function test (string, boolean) {
// any of these below will throw errors to protect you
not('string', string)
not('boolean', boolean)
// continue with your code.
}