Function isEmpty

Returns true if an array is empty.

Allows typescript to understand the array is empty when used in an if statement:

const arr = []
if (isEmpty(arr)) {
	// arr is []
} else {
	// arr is any[]
}
// more examples below
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Also useful for objects, but there is no way to get typescript to understand the object is empty.

const obj = {a:"a"}
if (isEmpty(keys(obj))) {
	// obj is still {a: string}
} else {
	// obj is {a: string}
}
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More examples of how this behaves with different array types:

const arr: any[] = [] // implicit any[]
if (isEmpty(arr)) arr // []
else arr // any[]

const arr = ["A"]
if (isEmpty(arr)) arr // []
else arr // string[]

const arr: [] = []
//       ^ required for non-const arrays
if (isEmpty(arr)) arr // []
else arr // never

const arr: ["A"] = ["A"]
//       ^ required for non-const arrays
if (isEmpty(arr)) arr // never
else arr // ["A"]

const arr = [] as const
if (isEmpty(arr)) arr // readonly []
else arr // never

const arr = ["A"] as const
if (isEmpty(arr)) arr // never
else arr // readonly ["A"]
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