slickgrid 中ajax,为什么Slickgrid Ajax /无限滚动会产生间歇空白行？
在slickgrid RemoteModel示例中的ensureData(from，to)方法中存在一个错误，但我不记得具体是什么。为了更有效地使用后端数据库，我对其进行了更正。下面是代码：
/** Ensures data range is loaded, loading if necessary. */
function ensureData(from, to) {
// Reduce range to only unloaded data by eliminating already loaded data at the extremes
// or data which is already being loaded by a pending request
if (from < 0) {from = 0;}
while (data[from] !== undefined && from < to) {from++;}
while (data[to] !== undefined && from < to) {to--;}
// no need to load anything
if (data[from] !== undefined) {
return;
}
// A request for data must be made: increase range if below optimal request size
// to decrease number of requests to the database
var size = to - from + 1;
if (size < optimalRequestRangeSize) {
// expand range in both directions to make it equal to the optimal size
var expansion = Math.round((optimalRequestRangeSize - size)/2);
from -= expansion;
to += expansion;
// if range expansion results in 'from' being less than 0,
// make it to 0 and transfer its value to 'to' to keep the range size
if (from < 0) {
to -= from;
from = 0;
}
// Slide range up or down if data is already loaded or being loaded at the top or bottom...
if (data[from] !== undefined) {
while (data[from] !== undefined) {
from++;
to++;
}
}
else if (data[to] !== undefined) {
while (data[to] !== undefined && from > 0) {
from--;
to--;
}
}
}
// After adding look-ahead and look-behind, reduce range again to only unloaded
// data by eliminating already loaded data at the extremes
while (data[from] !== undefined && from < to) {from++;}
while (data[to] !== undefined && from < to) {to--;}
// clear any pending request
if (request !== null)
clearTimeout(request);
// launch request to server with a delay of 100ms to cater with quick scrolling down
request = setTimeout(function() {
requests++;
// set records in range to null; null indicates a 'requested but not available yet'
for (var i = from; i <= to; i++) {
if (!data[i]) {
data[i] = null;
}
}
// notify grid (to show loading message) and load through ajax
onDataLoading.notify({from: from, to: to});
$.ajax({
url: url,
global: false,
cache: true,
type: "GET",
data: {
from: from,
to: to,
sortColumn: sortColumn,
sortDirection: sortDirection
},
dataType: "xml",
success: function(response, textStatus, jqXHR) {
if (requests > 0) requests--;
onSuccess(response, textStatus, jqXHR)
},
error: function(jqXHR, textStatus, errorThrown) {
if (requests > 0) requests--;
if (textStatus !== "abort") {
onDataLoadingError.notify({
from: from, to: to, pendingRequests:requests,
textStatus: textStatus, errorThrown: errorThrown
});
}
}
});
}, 100);
}
希望这有助于。