One exciting feature introduced in jQuery 1.5 is the ability to enhance the $.ajax functionality through prefilters. The idea was sparked by a desire to display a message for a minimum duration when an ajax call is initiated.
With the use of prefilters, it became possible to include a property called "delayedSuccess" in the ajax call, along with a specified time in milliseconds. This designated time serves as the minimum waiting period before triggering the success function upon completion of the ajax call. For example, if a delay of 3000 milliseconds (3 seconds) is specified and the actual call only takes 1.3 seconds, the success function will be delayed by 1.7 seconds. However, if the initial ajax call exceeds 3 seconds, the success function will execute immediately.
The implementation of this concept involves creating an ajax prefilter as outlined below:
$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
if (originalOptions.delaySuccess && $.isFunction(originalOptions.success)) {
var start, stop;
options.beforeSend = function () {
start = new Date().getTime();
if ($.isFunction(originalOptions.beforeSend))
originalOptions.beforeSend();
};
options.success = function (response) {
var that = this, args = arguments;
stop = new Date().getTime();
function applySuccess() {
originalOptions.success.apply(that, args);
}
var difference = originalOptions.delaySuccess - (stop - start);
if (difference > 0)
setTimeout(applySuccess, difference);
else
applySuccess();
};
}
});
The process begins by checking whether the delaySuccess and success options have been configured. If so, the beforeSend callback is customized to record the current time as the starting point. Subsequently, the success function is modified to calculate the elapsed time post-ajax call and adjust it based on the specified delaySuccess value. Finally, a timeout mechanism is established to trigger the success function after the computed delay time.
This approach proved to be a practical solution for achieving the desired effect, offering flexibility for utilization across various sections of a website.