javascript: avoid nested in nested loops

Question

I have trouble getting my head around this code without making some ugly nested in nested loops.

I have the following:

var selected_ingredients = [ {name:'ing4},{name:'ing13},{name:'ing14},{name:'ing21},{name:'ing23} ];

var pizza = [ {name:'pizza1',ing[ {name:'ing12},{name:'ing2} ]}, {name:'pizza2',ing[ {name:'ing4},{name:'ing13} ]}, {name:'pizza3',ing[ {name:'ing14},{name:'ing21},{name:'ing2} ]}, {name:'pizza4',ing[ {name:'ing14},{name:'ing3} ]}, {name:'pizza5',ing[ {name:'ing21},{name:'ing14},{name:'ing5} ]} ];

I want the following:

i want the code only to printout the pizzas that have the same ingredients that can be found in selected_ingredients array.

how should I do this code with without making the code slow from all the loops in loops also when the arrays can contain 1000 of pizza items.

The code in the question is riddled with syntax errors. So the first thing is to correct those so we have an idea what the real structure is. — T.J. Crowder, Sep 19 '16 at 16:13
@T.J.Crowder copy&paste problems I guess. But it's true that he needs to fix them! — Marcos Pérez Gude, Sep 19 '16 at 16:14
However, this is a very simple task with SQL, if WebSQL be a reality :'( — Marcos Pérez Gude, Sep 19 '16 at 16:15
It looks like you just want to loop over pizzas and then compare the list of ingredients to the full ingredients array. Other questions like http://stackoverflow.com/questions/7837456/how-to-compare-arrays-in-javascript are probably enough to get you going. — Andy Ray, Sep 19 '16 at 16:16
Thats just example code. The issue is that i have array in array which i have to loop through (ingredients in pizzas) While i have to loop through the selected_ingredients. To make sure that i printout The right pizzas. It Will become a nested loop hell. How do I make this clean code? — lars peterson, Sep 19 '16 at 16:35

score 0 · Answer 1 · answered Sep 19 '16 at 17:54

You can use a map (works in modern browsers).

var map = new Map();
for (var i=0; i < pizza.length; i++) {
  var ingString = JSON.stringify(pizza[i].ing);
  var pizzaWithIng = map.get(ingString);
  if (!pizzaWithIng) {
    pizzaWithIng = [];
    map.set(ingString, pizzaWithIng);
  }
  pizzaWithIng.push(pizza[i]);
}

var result = map.get(JSON.stringify(selected_ingredients));

The solution requires that the ingredients are sorted.

Sudharsan Selvaraj · Accepted Answer · 2016-09-19T16:33:46.823

You can use .filter() method to filter an array based on any conditions. Look at below example code.

var filtered_result = pizza.filter(function(pizza_detail){
  return pizza_detail.ing.sort(arraySort) == selected_ingredients.sort(arraySort);
})

function arraySort(a,b){
  return a.attributes.name < b.attributes.name ? 1 : -1;
}

Since your Json objects are not sorted,you need to sort it before comparing it with selected_ingrediants array.

javascript: avoid nested in nested loops

2 Answers2