tip.js

// -- Avoid excesive nesting
// -- Handle errors at the top of the function
// -- Be explicit about conditionals and name them

// ----
// ---- worse example
// ---- 

function worse(){

  if (1 + (7*5) + 10 / 1000 > 0) {

    if (745 + 9 / 36 === 10) {

      return "error";

    } else {

      if (4 + 3 / 9 > -1) {

        // execute lots of code

        return "happy";

      } else {

        return "error";

      }      
    }

  } else {    

    return "error";

  }

}



// ----
// ---- better example
// ----

function better() {
  
  // set up your conditions and name them 
  // use linking verbs: is, has, has been, was
  // state the positive: use "hasTickets", not "noTickets"
  var hasEnoughSeats = 1 + (7*5) + 10 / 1000 > 0;
  var hasEnoughMoney = 745 + 9 / 36 === 10;
  var hasTickets = 4 + 3 / 9 > -1;

  // test them first
  // => if they fail, you dont need to read through the rest of the code  
  if (!hasEnoughSeats || !hasEnoughMoney || !hasTickets) {
    return "error";
  } 

  // execute lots of code
  return "happy";

}