Select from array of objects based on property value in JavaScript [duplicate]

Question

I have JSON objects that have several properties such as an id and name. I store them in a JavaScript array and then based on a dropdownlist I want to retrieve the object from the JavaScript array based on its id.

Suppose an object has id and name, how do I select them from my array variable?

var ObjectsList = data; var id = $("#DropDownList > option:selected").attr("value"); ObjectsList["id=" + id]; 

Answer 1

Since you already have jQuery, you could use $.grep:

Finds the elements of an array which satisfy a filter function. The original array is not affected.

So something like this:

var matches = $.grep(ObjectsList, function(e) { return e.id == id }); 

that will leave you with an array of matching entries from ObjectsList in the array matches. The above assumes that ObjectsList has a structure like this:

[     { id: ... },     { id: ... },     ... ] 

If you know that there is only one match or if you only want the first then you could do it this way:

for(var i = 0, m = null; i < ObjectsList.length; ++i) {     if(ObjectsList[i].id != wanted_id)         continue;     m = a[i];     break; } // m is now either null or the one you want 

There are a lot of variations on the for loop approach and a lot of people will wag a finger at me because they think continue is a bad word; if you don't like continue then you could do it this way:

for(var i = 0, m = null; i < ObjectsList.length; ++i) {     if(ObjectsList[i].id == wanted_id) {         m = ObjectsList[i];         break;     } }