Difference between bind(), apply() and call()

main.js

var a = 10; // A Global Variable
function p(z) {
  // a normal function that 
  // accepts a variable z as a parameter
  console.log(this.a, z);
}

// normal call
// this.a is 10 because GLOBAL variable
// and z = 1
p(1);

// bind
var b = p.bind({a:20});  // bind CREATES a new function with `this.a = 20`
                         // then you will need to execute the function separately
b(2);                    // executing the new created function with `z = 2`
// or
p.bind({a:30})(3);       // executing the function this way

p.apply({a:40}, [4]);    // apply CALLS the function with `this.a = 40` but you give ARRAY params
p.call({a:50}, 5);       // call CALLS  the function with `this.a = 50` but requires INDIVIDUAL params

// The Output is 
// 10 1 ( or `undefined 1` if you are running it in node)
// 20 2
// 30 3
// 40 4
// 50 5