how to identify an objects place within an array

Question

I load an array of objects into a select box. The user makes a selection... how can identify which array object they chose so I can use it in downstream work?

For example if user chooses the 2nd object in the array... how can identify the selection was the second item in the array?

http://jsfiddle.net/silvajeff/LRXkV/3/

angular.module('demoApp', []).controller('DemoController', function ($scope) {

$scope.captions = [{
    name: 'A',
    value: 'a'
}, {
    name: 'B',
    value: 'b'
}, {
    name: 'C',
    value: 'c'
}, {
    name: 'D',
    value: 'd'
}, {
    name: 'E',
    value: 'e'
}];

//how could I determine that 3 should be the number used in the expression below
$scope.selectedCaption = $scope.captions[3];
});

why dont you simply pass the caption object the user clicked on? Otherwise you would have to search through the array or use the $index property of ng-repeat — pfried
– pfried, Commented Jul 19, 2014 at 12:26
Unfortunately in my scenario the caption is not useful for what I ultimately need to do. This is a simplification of the problem, but I was just wondering if there was anyway for angular or javascript to get the object number. — silvster27
– silvster27, Commented Jul 19, 2014 at 12:41

IUnknown · Accepted Answer · 2014-07-19 12:46:08Z

1

You can wotch for index of selected item in array:

$scope.$watch(function() {
    return $scope.captions.indexOf($scope.selectedCaption);
  },
  function(newVal, oldVal) {
    if (newVal != oldVal) {
      alert('New index of selected caption :' + newVal);
    }
  });

Or just watch for selectedCaption anf get index in listener function:

$scope.$watch('selectedCaption',
function (newVal, oldVal) {
    if (newVal != oldVal) {
        alert('New index of selected caption :' + $scope.captions.indexOf(newVal));
    }
});

answered Jul 19, 2014 at 12:46

IUnknown

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Comments

plalx · Accepted Answer · 2014-07-19 12:32:28Z

0

Your code was in the body's onload so the module wasn't even properly initialized, that's why your fiddle wasn't working.

$scope.selectedCaption is the select's model and will be automatically updated as the select value changes.

http://jsfiddle.net/LRXkV/2/

edited Jul 19, 2014 at 12:32

answered Jul 19, 2014 at 12:26

plalx

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1 Comment

silvster27 Over a year ago

oops. Here's the updated fiddle... this still doesn't answer the question I need to find the object # in the array. The reason for this has to do with me needing to reload that array and setting it's initial value to the previous selection. jsfiddle.net/silvajeff/LRXkV/3

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