Question

I have an array of objects in javascript. The objects contain some properties and look something like this :

  { "Name" : "blabla", "Id": "1" }

Now I have a function which accepts a single parameter that will be the Name property value of the object. The function looks somethings like this :

     function CheckForExistance(array, name){
       var exist = false;

       $.each(array, function(index, value){
          if(value.Name == name)
          {
             exist = true;
             return false;
          }
       });
       return exist;
     }

I want to know if there is a better way to do this ?

Answer 1

You can use $.grep() to filter down the array to a match, and return a comparison of the .length.

 function CheckForExistance(array, name){
     return $.grep(array, function(obj) {
         return obj.Name == name;
     }).length > 0;
 }

Or native methods are a little nicer IMO, but you’ll need a shim for old browsers.

function CheckForExistance(array, name){
    return array.some(function(obj) {
        return obj.Name == name;
    });
}

This one uses Array.prototype.some, and will exit as soon as a truthy return value is given, and will then return true. If no truthy return is found, then it’ll return false.

---

FWIW, you can make your function a little more robust by providing a dynamic property name as well.

function CheckForExistance(array, prop, val){
    return array.some(function(obj) {
        return obj[prop] == val;
    });
}

Then use it to check any property value.

var found = CheckForExistance(myArray, "Name", "blabla");

---

Or another approach would be to make a function factory that creates functions to be used with iterators.

function havePropValue(prop, value) {
    return function(obj) {
        return obj[prop] == value;
    };
}

Then we can just use .some() directly without needing the CheckForExistance function.

var found = myArray.some(havePropValue("Name", "blabla"));

Or with $.grep.

var found = $.grep(myArray, havePropValue("Name", "blabla")).length > 0;