jQuery-滚动时附加和删除html内容

Question

Question: how can i calculate scroll position after deleting (with jquery) some lines at the beginning of a html file - scroll position which will provide view at the same lines as before deleting.

situation overview: I have generated HTML page, but i have problems because that generated page may have up to 200MB. So i want to: + hold all the data in the JS's Array + append content at the end and delete at the beginning dynamically while scrolling down + append content at the beginning and delete at the end while scrolling up

Operations with page beginning are making some unpredictable scrolls to different page parts. Here's my code, but i don't feel it's well - there're a lot of unused variables. Note that I'm appending lines from array DataLines + in visibleDataLinesNumbers i have indexes of lines which should be shown (there're also some hide/show selected lines functionality). Every line has also its id connected with index in DataLines (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;
    }
}

Answer 1

看一下该脚本： https : //github.com/CardinalPath/gas/blob/master/src/plugins/max_scroll.js问候