SOURCE

var n1 = 5, v1 = 5;
var n2 = 6, v2 = 6;

//prefix: returns the value after increment/decrement
var n3 = --n1 + n2; //10
var n4 = n1 + n2; //10
console.log(n3);
console.log(n4);

//suffix: returns the value before increment/decrement
var v3 = v1-- + v2; //11
var v4 = v1 + v2; //10
console.log(v3);
console.log(v4);