Two-way binding with range and number input in AngularJS

All we need is an easy explanation of the problem, so here it is.

I’m just starting to play around with AngularJS and trying to understand the binding technique. For starters, I tried to make a simple conversion calculator (dozens to pieces, pieces to dozens). That worked well, but when I tried to bind both a range input and a number input to the same model property the number input does not update when the range value is adjusted. I have a jsfiddle showing the behavior:

common javascript for broken and working fiddles:

var myApp = angular.module('myApp', []);

myApp.controller('CalcCtrl', function ($scope) {
    var num = 0.0;
    $scope.qty = new Quantity(12);
    $scope.num = num;
});

function Quantity(numOfPcs) {
    var qty = numOfPcs;
    var dozens = numOfPcs / 12;

    this.__defineGetter__("qty", function () {
        return qty;
    });

    this.__defineSetter__("qty", function (val) {
        qty = val;
        dozens = val / 12;
    });

    this.__defineGetter__("dozens", function () {
        return dozens;
    });

    this.__defineSetter__("dozens", function (val) {
        dozens = val;
        qty = val * 12;
    });
}

BROKEN FIDDLE

html:

<div ng-controller="CalcCtrl">
    <form>
        <label for="pcs">Pieces:</label>
        <input type="number" min="0" ng-model="qty.qty" size="20" id="pcs"
        />
        <input type="range" min="0" max="100" ng-model="qty.qty" />
        <br/>
        <label for="numOfDozens">Dozens</label>
        <input type="number" min="0" ng-model="qty.dozens" size="20"
        id="numOfDozens" />
    </form>
</div>

However, binding two number inputs to the same model property seems to work fine as shown in this fiddle:

WORKING FIDDLE

html:

<div ng-controller="CalcCtrl">
    <form>
        <label for="pcs">Pieces:</label>
        <input type="number" min="0" ng-model="qty.qty" size="20" id="pcs"
        />
        <input type="number" min="0" max="100" ng-model="qty.qty" />
        <br/>
        <label for="numOfDozens">Dozens</label>
        <input type="number" min="0" ng-model="qty.dozens" size="20"
        id="numOfDozens" />
    </form>
</div>

Any ideas how to get a range and number input bound to a single model property in AngularJS? Thanks.

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

The problem here is that the input type=”range” works with Strings and not with Numbers (while input type=”number” only works with Numbers).

http://www.w3.org/wiki/HTML/Elements/input/range

The range state represents a control for setting the element’s value to
a string representing a number.

If you add val = parseInt(val) as your first instruction on the qty setter it should work:

this.__defineSetter__("qty", function (val) {        
    val = parseInt(val);
    qty = val;
    dozens = val / 12;
});

jsfiddle: http://jsfiddle.net/bmleite/2Pk3M/2/

Method 2

I think this solution is more generic.

myApp.directive('input', function() {
return {
    restrict: 'E',
    require: '?ngModel',
    link: function(scope, element, attrs, ngModel) {
        if ('type' in attrs && attrs.type.toLowerCase() === 'range') {
            ngModel.$parsers.push(parseFloat);
        }
    }
};

});

full explanation

Method 3

You can solve it using ng-model-options. I changed jsfiddle and here is the code:

html:

<div ng-controller="CalcCtrl">
    <form>
        <label for="pcs">Pieces:</label>
        <input type="number" min="0" ng-model="qty.qty" size="20" id="pcs" ng-model-options="{ getterSetter: true }"/>
        <input type="range" min="0" max="100" ng-model="qty.qty" ng-model-options="{ getterSetter: true }"/>
        <br/>
        <label for="numOfDozens">Dozens</label>
        <input type="number" min="0" ng-model="qty.dozens" size="20"
        id="numOfDozens" ng-model-options="{ getterSetter: true }"/>
    </form>
</div>

js:

var myApp = angular.module('myApp', []);

myApp.controller('CalcCtrl', function ($scope) {
    var num = 1.0;
    $scope.qty = {
    qty:function (val) {
        return arguments.length ? (num = parseFloat(val)) : num;
     }, 
     dozens: function (val) {
            return arguments.length ? (num = val*12) : num/12;
        }
     };
});

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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