Use built-in JavaScript operators to determine the type at runtime:

function checkType(value: any): void {
  if (typeof value === "string") {
    console.log("Value is a string");
  } else if (typeof value === "number") {
    console.log("Value is a number");
  }
  // And so on…
}

checkType("test"); // Output: Value is a string
Type Check
string typeof s === "string"
number typeof n === "number"
boolean typeof b === "boolean"
undefined typeof u === "undefined"
function typeof f === "function"
array Array.isArray(a)