Getting MathJax to update after changes to AngularJS model

Solution 1:

Having wasted many days (and maybe weeks) fighting MathJax, I'm all too familiar with its various quirks with updating math expressions on the fly. I'm brand new to Angular but this gave me a good chance to dive in and I ended up with a solution which solves my problems -- hopefully it'll solve yours as well.

Live demo: jsfiddle

Instead of using the plain interpolation that Angular provides, I created a new directive based on ng-bind called mathjax-bind.

If expression is a variable containing math code, then instead of \( {{expression}} \) you can write:

<span mathjax-bind="expression"></span>

and everything will be typeset and updated at the appropriate times.

The supporting code for the directive follows:

myApp.directive("mathjaxBind", function() {
    return {
        restrict: "A",
        controller: ["$scope", "$element", "$attrs",
                function($scope, $element, $attrs) {
            $scope.$watch($attrs.mathjaxBind, function(texExpression) {
                var texScript = angular.element("<script type='math/tex'>")
                    .html(texExpression ? texExpression :  "");
                $element.html("");
                $element.append(texScript);
                MathJax.Hub.Queue(["Reprocess", MathJax.Hub, $element[0]]);
            });
        }]
    };
});

Solution 2:

Simplest, fastest and most stable solution:

$rootScope.$watch(function(){
  MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
  return true;
});

Advantages:

• Easy to setup, just copy this code.
• Everything on your page is typeset.
• It renders much faster than the other solutions. This is because it can render the page in one go. Other answers here wait for one item to finish, until they typeset the next one. That makes rendering veeeery slow if there are for example multiple mathjax-bind directives (as another answer suggests). This point is the reason I was looking for a different answer.
• You can still easily exclude elements using the option “ignoreClass” in your mathjax settings.

Benchmarking: 100 mathjax-bind directives took 63 seconds, while with this method it took 1.5 second to render the page. I know that this function will be executed a lot since it's called on every digest cycle, however, it doesn't noticeably slow down the page.