typeof param[key] typescript

This code snippet is checking the type of a property named `key` in the object `param` using TypeScript.

Assuming `param` is an object and `key` is a string representing one of its properties, the `typeof` keyword is used to return the data type of the value stored in that property.

For example, if `param[key]` is a string, `typeof param[key]` would return `"string"`. If it is a number, `typeof param[key]` would return `"number"`, and so on.