Question

consider the following:

 var service_call_array = { 
     3 : 'test',
     4 : 'more of a test eh?',
     5 : 'more info required'
 }; 

I can loop through it thus

$(function() { 
   $.each(service_call_array, function(key, value) {
        alert(key + ':' +value);
   }
});

but how in principle, I would add a fourth item key:value, how can I update or edit or change a value by key (say key:4) how can I remove by referencing the key, and how can I reference an elements value by the key without looping?

thanks in advance

Answer 1

First of all, that’s an object – not an array. Arrays can only have numerical indices and have special semantics such as a .length property. Now, to answer your question.

What you have there is a plain old JavaScript object, and you’re assigning properties on it. MDN has a complete page about them. Here’s a summary:

Accessing properties

Use the o.key or o["key"] syntax, for example:

var object = {
    foo: "bar"
};
alert(object.foo); // displays "bar"

The o["key"] syntax is particularly handy when using the object as a lookup table, for example:

var translate = {
    "hello": "bonjour",
    "goodbye": "au revoir"
};
var word = "hello"; // received through some kind of user input
alert(translate[word]); // displays "bonjour"

Setting properties

Similar to accessing properties, but now you place them on the left hand side of the assignment. It doesn’t really matter whether the property already exists or not, it will be created if necessary.

var object = {};
object.foo = "bar";
alert(object.foo); // still "bar"

Deleting properties

Use the delete statement.

var object = {
    foo: "bar"
}
alert(object.foo); // displays "bar"
delete object.foo;
alert(object.foo); // displays "undefined"
alert(object.foo === undefined); // displays true