Is there a safe delay in JavaScript?

Question

A way that doesn't hog resources, just stops execution for 1 second then executes?

What I want to do is dynamically move a Google gauge from one value to another, creating the effect of it moving to the value instead of jumping to it.

i.e. -

for(original_value; original_value < new_value; original_value++)
{
    data.setValue(0, 1, original_value);
    delay half a second here in JavaScript?
}  

Is this an OK way of doing this or is something closer to what the demo is doing is extremely better? :
http://stackoverflow.com/questions/3485095/how-to-dynamically-move-google-gauge

Answer 1

No. JavaScript in web browsers is not only single threaded, but it shares the same thread with the browser rendering. If your JavaScript code were to block, the browser UI would become unresponsive during that period.

The typical way to tackle time-based events in JavaScript is by using asynchronous timers. John Resig wrote an intresting article a while ago called "How JavaScript Timers Work", which you may want to check out.

---

UPDATE:

Are you using the Google Visualization API for the guages? If so, it seems to me that Google already handles the smooth animation that you're trying to achieve. Try the following in the Google Code Playground (keep an eye on the Network gauge):

function drawVisualization() {
  // Create and populate the data table.
  var data = new google.visualization.DataTable();
  var chart;

  data.addColumn('string', 'Label');
  data.addColumn('number', 'Value');
  data.addRows(3);
  data.setValue(0, 0, 'Memory');
  data.setValue(0, 1, 80);
  data.setValue(1, 0, 'CPU');
  data.setValue(1, 1, 55);
  data.setValue(2, 0, 'Network');
  data.setValue(2, 1, 68);

  // Change the value of the Network Gauge after 3 seconds.
  setTimeout(function () { data.setValue(2, 1, 20); chart.draw(data); }, 3000);

  // Create and draw the visualization.
  chart = new google.visualization.Gauge(document.getElementById('visualization'));
  chart.draw(data);
}

Answer 2

This should work.

var id, value = original_value;
id = setInterval(function() {
    if (value < new_value) {
        data.setValue(0, 1, value++);
    } else {
        clearInterval(id);
    }
}, 1000);