问题:如何在删除(使用jquery)html文件开头的某些行后计算滚动位置 - 滚动位置将提供与删除前相同行的视图。
情况概述: 我已生成HTML页面,但我遇到了问题,因为生成的页面可能最多 200MB。所以我想: +保存JS数组中的所有数据 +在向下追加内容并在向下滚动时动态删除 +在开头添加内容,在向上滚动时删除
页面开头的操作会使一些不可预测的滚动到不同的页面部分。 这是我的代码,但我感觉不太好 - 有很多未使用的变量。 请注意,我在数据DataLines +中附加了在visibleDataLinesNumbers中的行,我有应该显示的行索引(还有一些隐藏/显示选定的行功能)。每一行的id都与DataLines中的索引相关联(id =“l”+ indexFromDataLine)
var howManyLinesToAppend = 100;
var howManyLinesToDelete = 300;
var whenAppendInPercent = 8/10;
var contentHeightMax = 15000;
var logLineDivHeight;
var lastScrollTop = 0;
window.onscroll = scrollHandling;
function scrollHandling() {
var contentHeight = document.getElementById("log").offsetHeight;
var yOffset = window.pageYOffset;
var yPosition = yOffset + window.innerHeight;
var st = $(this).scrollTop();
if (st > lastScrollTop) {
downscrollHandling(contentHeight, yOffset, yPosition);
}
else {
upscrollHandling(contentHeight, yOffset, yPosition);
}
lastScrollTop = st;
}
function downscrollHandling(contentHeight, yOffset, yPosition) {
appendDataLinesAtTheEndWhileScrolling(contentHeight, yOffset, yPosition);
deleteDataLinesAtTheBeginningWhileScrolling(contentHeight, yOffset, yPosition);
}
function upscrollHandling(contentHeight, yOffset, yPosition) {
appendDataLinesAtTheBeginningWhileScrolling(contentHeight, yOffset, yPosition);
deleteDataLinesAtTheEndWhileScrolling(contentHeight, yOffset, yPosition);
}
function appendDataLinesAtTheBeginningWhileScrolling(contentHeight, yOffset, yPosition) {
if(lowerBoundOfLinesOnScreen != 0 && yPosition < (1-whenAppendInPercent)*contentHeight) {
var tmp ="";
var startingLowerBoundOfLinesOnScreen = lowerBoundOfLinesOnScreen;
for(var i = startingLowerBoundOfLinesOnScreen - howManyLinesToAppend; i < startingLowerBoundOfLinesOnScreen; i++)
tmp += DataLines[visibleLinesNumbers[i]];
lowerBoundOfLinesOnScreen -= howManyLinesToAppend;
$("#l"+startingLowerBoundOfLinesOnScreen).before(tmp);
}
}
function deleteDataLinesAtTheEndWhileScrolling(contentHeight, yOffset, yPosition) {
if(contentHeight > contentHeightMax) {
for(var i = upperBoundOfLinesOnScreen - howManyLinesToDelete; i < upperBoundOfLinesOnScreen; i++)
$("#l"+visibleLinesNumbers[i]).remove();
upperBoundOfLinesOnScreen -= howManyLinesToDelete;
}
}
function appendDataLinesAtTheEndWhileScrolling(contentHeight, yOffset, yPosition) {
if( yPosition >= contentHeight * whenAppendInPercent ) {
showDataLines(howManyLinesToAppend);
}
}
function deleteDataLinesAtTheBeginningWhileScrolling(contentHeight, yOffset, yPosition) {
if(contentHeight > contentHeightMax) {
for(var i = lowerBoundOfLinesOnScreen; i < lowerBoundOfLinesOnScreen + howManyLinesToDelete; i++) {
$("#l"+visibleLinesNumbers[i]).remove();
}
lowerBoundOfLinesOnScreen += howManyLinesToDelete;
}
}
答案 0 :(得分:1)