滚动到顶部功能时添加最小高度

Question

I have this JS code which scrolls to the div whenever clicked. However it shows the DIV at the top. This creates a problem since I have a fixed header which is 90px in height and the div goes behind it; the title of the DIV is hidden.

I would like to modify this code so that the DIV doesn't scroll to the very top but leaves a certain height of say 90px. See the screenshot and notice how it hides behind the fixed header:

This is the Jasvascript:

this.scrollTo = function(eID) {

        // This scrolling function
        // is from http://www.itnewb.com/tutorial/Creating-the-Smooth-Scroll-Effect-with-JavaScript

        var startY = currentYPosition();
        var stopY = elmYPosition(eID);
        var distance = stopY > startY ? stopY - startY : startY - stopY;
        if (distance < 100) {
            scrollTo(0, stopY); return;
        }
        var speed = Math.round(distance / 100);
        if (speed >= 20) speed = 20;
        var step = Math.round(distance / 25);
        var leapY = stopY > startY ? startY + step : startY - step;
        var timer = 0;
        if (stopY > startY) {
            for ( var i=startY; i<stopY; i+=step ) {
                setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
                leapY += step; if (leapY > stopY) leapY = stopY; timer++;
            } return;
        }
        for ( var i=startY; i>stopY; i-=step ) {
            setTimeout("window.scrollTo(0, "+leapY+")", timer * speed);
            leapY -= step; if (leapY < stopY) leapY = stopY; timer++;
        }

        function currentYPosition() {
            // Firefox, Chrome, Opera, Safari
            if (self.pageYOffset) return self.pageYOffset;
            // Internet Explorer 6 - standards mode
            if (document.documentElement && document.documentElement.scrollTop)
                return document.documentElement.scrollTop;
            // Internet Explorer 6, 7 and 8
            if (document.body.scrollTop) return document.body.scrollTop;
            return 0;
        }

        function elmYPosition(eID) {
            var elm = document.getElementById(eID);
            var y = elm.offsetTop;
            var node = elm;
            while (node.offsetParent && node.offsetParent != document.body) {
                node = node.offsetParent;
                y += node.offsetTop;
            } return y;
        }

    };

Answer 1

You may be able to get away with just modifying your code to change this line:

var stopY = elmYPosition(eID);

to this:

var stopY = elmYPosition(eID) - 90;