---
layout: default
title: Example Timing Callback (page-local)
demojs : exp_timingcallback
---

<style>
.enabled {
  font-weight: bold;
}
.disabled {
  font-weight: normal;
}
</style>

- [Timing Callback API](api_timingcallback.html)

**setPointCallback** and **setIntervalCallback** are simple tools inspired by _setTimeout_ and _setInterval_. setPointCallback triggers a callback when the timing object passes by a specific point on the timeline. setIntervalCallback is associated with periodic points along the timeline.


#### Demo

**Timing Object**

<p>
  <button id="play">Play</button>
  <button id="pause">Pause</button>
  <button id="reset">Reset</button>
  <button id="backwards">Backwards</button>
</p>
<div style="font-weight:bold" id="value"></div>

**SetPointCallback**
<p>
  <button id="setpointcallbackonce" class="enabled">SetPointCallbackOnce</button>
  <button id="cancelpointcallbackonce" class="disabled" disabled="true">CancelPointCallbackOnce</button>
</p>
<p>
  <button id="setpointcallbackrepeat" class="enabled">SetPointCallbackRepeat</button>
  <button id="cancelpointcallbackrepeat" class="disabled" disabled="true">CancelPointCallbackRepeat</button>
</p>
<ul>
  <li>SetPointCallbackOnce generates a callback the first time position 4 is reached.</li>
  <li>SetPointCallbackRepeat generates a callback every time position 6 is reached.</li>
</ul>

**SetIntervalCallback**
<p>
  <button id="setintervalcallback" class="enabled">SetIntervalCallback</button>
  <button id="cancelintervalcallback" class="disabled" disabled="true">CancelIntervalCallback</button>
</p>
<ul>
  <li>SetIntervalCallback is set up with length 6 and offset 2, generating <i>periodical</i> callbacks at ...,2,8,14,20,...</li>
</ul>

**Callback Log**
<ul id="log">
</ul>


#### JavaScript

```javascript
TIMINGSRC.setPointCallback(to, function () {
	append("point callback (once) at position " + to.query().position.toFixed(2));
}, 4);

TIMINGSRC.setPointCallback(to, function () {
    append("point callback (repeated) at position " + to.query().position.toFixed(2));
}, 6, {repeat:true});

TIMINGSRC.setIntervalCallback(to, function () {
    append("interval callback at position " + to.query().position.toFixed(2));
}, 6, {offset:2});
```