How to iterate through nested objects in JS

Question

Ok I'm stumped on this one. I need to iterate through these so I can make a listing by the category so something like

Business Books

Book 1

Book 2

Book 3

Cooking Books

etc..

But couldn't figure out how to iterate through the nested objects. With or without jquery is fine

window.books = {
    "Business Books": [
       {
           Title: "Finance 101",
           Description: "Info for Finance 101 book goes here."
       },
       {
           Title: "Economics 123",
           Description: "Info for Economics 123 book goes here."
       },
       {
           Title: "Statistics for Beginners",
           Description: "Learn about Statistics."
       }
    ],
    "Cooking Books": [
       {
           Title: "Lowfat Treats",
           Description: "Eat a lowfat Diet"
       },
       {
           Title: "Chocolate Lovers",
           Description: "Eat a lot of chocolate"
       },
       {
           Title: "Book of Brownies",
           Description: "Stuff about Brownies"
       }
    ],
    "IT Books": [
       {
           Title: "Windows XP",
           Description: "Please go away"
       },
       {
           Title: "Linux",
           Description: "A how to guide."
       },
       {
           Title: "Unix",
           Description: "All about Unix."
       },
       {
           Title: "Mac",
           Description: "Costs too much."
       }
    ],
};

Iterate over the properties of the object. Each has as value an array of objects. Iterate over the array. This requires a nested for loop. Have a look at developer.mozilla.org/en/JavaScript/Guide/… — Felix Kling
– Felix Kling, Commented Jun 27, 2012 at 16:28

mvbl fst · Accepted Answer · 2012-06-27 16:27:06Z

10

Good idea is to learn how to do it without jQuery first.

for(var category in window.books) {
  if(window.books.hasOwnProperty(category)) {
    console.log(category); // will log "Business Books" etc.
    for (var i = 0, j = window.books[category].length; i < j; i++) {
      console.log("Title: %s, Description: %s", window.books[category][i].Title, window.books[category][i].Description);
    }
  }
}

Then you can use $.each().

answered Jun 27, 2012 at 16:27

mvbl fst

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Comments

Jashwant · Accepted Answer · 2012-06-27 16:34:46Z

2

$.each(window.books,function(k,v){   // k ==== key, v === value
        // Prints category
        console.log(k); 

        //Loops through category
        for(i=0,len=v.length;i<len;i++){
            console.log(v[i].Title);
            console.log(v[i].Description);
        }
    });

answered Jun 27, 2012 at 16:34

Jashwant

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Comments

Donatas Olsevičius · Accepted Answer · 2012-06-27 16:25:32Z

1

jQuery.each(window.books, function(category, items) {
    alert(category);

    jQuery.each(items, function(idx, book) {
        alert(category + ': ' + book.Title)
    });
});

answered Jun 27, 2012 at 16:25

Donatas Olsevičius

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Comments

Sam Tyson · Accepted Answer · 2012-06-27 16:32:51Z

0

Looping with .each() is pretty easy:

$.each(window.books, function(category, books) {                                    
    $("#books").append("<p>" + category + "</p><ul>");                              
    $.each(books, function(i, book) {                                               
        $("#books").append("<li>" + book.Title + ": " + book.Description + "</li>");
    });                                                                             
    $("#books").append("</ul>");                                                    
});

here is my jsFiddle

answered Jun 27, 2012 at 16:32

Sam Tyson

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