Eric Schaefer

How to Render jQuery Flot Charts through AngularJS

There are lots of javascript data visualization and charting libries out there, but only a couple bother to minimize the IE8 compatability headache. Flot Charts seems to work nicely for my purposes on this particular project. I need bar charts and donut charts, both of which Flot handles well.

Thing is, I really want to use AngularJS for the project I’m working on right now. I don’t know of any Angular-native charting libraries (though that would be a killer addition to Angular UI). Now I’m faced with the added layer of wrapping a jQuery plugin inside of Angular functions. What?

Luckily AngularJS can render Flot through a unique feature called a directive. Stackoverflow user jm- got me started in the right direction on this. I’ve expanded his example in my own JSFiddle, which renders a bar chart through AngularJS.

If you’ve worked with Flot before in regular ol’ jQuery, then you’re probably familiar with the Flot API. If you’re new to Flot, then give the API a quick read. You can customize pretty much anything in your graph/chart with it.

Here’s some example DOM markup:

<div ng-app='App'>
    <div ng-controller='barChartController'>
        <chart ng-model='data'></chart>
    </div>
</div>

Then the AngularJS:

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

App.controller('barChartController', function($scope){

    var daftPoints = [[0, 4]],
    	punkPoints = [[1, 20]];

    var data1 = [
        {
            data: daftPoints,
            color: '#00b9d7',
            bars: {show: true, barWidth:1, fillColor: '#00b9d7', order: 1, align: "center" }
        },
        {
            data: punkPoints,
            color: '#3a4452',
            bars: {show: true, barWidth:1, fillColor: '#3a4452', order: 2, align: "center" }
        }
    ];

    $scope.data = data1;


});

App.directive('chart', function(){
    return{
        restrict: 'E',
        link: function(scope, elem, attrs){

            var chart = null,
                options = {
                xaxis: {
                    ticks:[[0,'Daft'],[1,'Punk']]
                },
                grid: {
                  labelMargin: 10,
                  backgroundColor: '#e2e6e9',
                  color: '#ffffff',
                  borderColor: null
                }
              };

            var data = scope[attrs.ngModel];

            // If the data changes somehow, update it in the chart
            scope.$watch('data', function(v){
                 if(!chart){
                    chart = $.plot(elem, v , options);
                    elem.show();
                }else{
                    chart.setData(v);
                    chart.setupGrid();
                    chart.draw();
                }
            });
        }
    };
});

How to get this to work on IE8

  1. Add id="ng-app" to the document’s root element in conjunction with ng-app attribute
<!DOCTYPE html>
<html lang="en" xmlns:ng="http://angularjs.org" id="ng-app" ng-app="App">
...
</html>
  1. Load the AngularUI IE shiv, at the bottom of your javascript file list, in an IE8-targeted comment, and declare the chart directive. IE8 won’t load that <chart> element without this.
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.7/angular.min.js"></script>
<script src="js/application.js"></script>
...
<!--[if lte IE 8]>
    <script>
    // Declare custom directive names and load shiv for AngularJS in here. Or else IE8 bummertown.
    window.myCustomTags = [ 'chart' ];
	</script>
    <script src="js/ie-shiv.js"></script>
<![endif]-->
...
<body>
	...