what is an immediately invoked function in javascript code example

Example 1: javascript Immediately Invoked Function Expression

result = (function(a, b){
    return a - b;
})(100, 42);

console.log(result); // 58

Example 2: Immediately-Invoked Function javascript

(() => {
  /* */
})()

Example 3: Immediately-Invoked Function javascript

(function() {
  /* */
})()