calling javascript on rendering views in BackBone js. post-render callback?

Question

behold, a backbone view render call:

render: function() {
  $(this.el).html(this.template({title: 'test'}));  //#1
  this.renderScatterChart();
  return this;
},

so, I call a standard render at #1. and then, i call a method [this time, it is a wrapper for charting lib] that looks for a div. the div is rendered by the render call. but at this point, it is not attached to the DOM yet (right?). so the chart call sadly dies.

what is the pattern for this? i'd love hear that there is a post-render callback. i've tried a few hacks around this, and sometimes i get the chart to work, but events don't bind.

Answer 1

My usual approach for this sort of thing is to use setTimeout with a timeout of zero to arrange for something to happen once the browser gets control again. Try this:

render: function() {
    $(this.el).html(this.template({title: 'test'}));

    var _this = this;
    setTimeout(function() {
        _this.renderScatterChart();
    }, 0);

    return this;
}

Or, if renderScatterChart is already bound to the appropriate this:

render: function() {
    $(this.el).html(this.template({title: 'test'}));
    setTimeout(this.renderScatterChart, 0);
    return this;
}

You can also use _.defer if you want to be more explicit about what you're up to:

defer _.defer(function, [*arguments])

Defers invoking the function until the current call stack has cleared, similar to using setTimeout with a delay of 0.

So you could also do it like this:

// Assuming that `renderScatterChart` is bound to the appropriate `this`...
render: function() {
    $(this.el).html(this.template({title: 'test'}));
    _(this.renderScatterChart).defer();
    return this;
}

// or if it isn't bound...
render: function() {
    $(this.el).html(this.template({title: 'test'}));

    var _this = this;
    _(function() {
        _this.renderScatterChart();
    }).defer();

    return this;
}