How to write a self invoked function in JavaScript

Self invoked functions are function that run on themselves without need to be called, the syntax to create self invoked functions is as follows;

(function(){
    // function body
})()

the runtime will run everything in a self invoked function's body

You can pass parameters to the function using the syntax below;

(function(params){

    // function body

})(params)

parameters will be made available to the function as any other argument