Answers for "js is function exists"

javascript check if function exists

//check if sayHello() function exists
if (typeof sayHello === "function") { 
    // This function exists
}

js check if function exists

if (typeof yourFunctionName == 'function') { 
  yourFunctionName(); 
}

check if function exists javascript

if (typeof payment === "function")
{
  // Do something
}

function exists javascript

How to check if function exists in JavaScript?