what is !function in js code example

Example 1: function javascript

var x = myFunction(4, 3);     // Function is called, return value will end up in x

function myFunction(a, b) {
    return a * b;             // Function returns the product of a and b
}

Example 2: define function in javascript

/* Declare function */
function myFunc(param) {
  // Statements 
}