本文实例讲述了JS实现放大、缩小及拖拽图片的方法。分享给大家供大家参考，具体如下：

var divId; var v_left; var v_top; window.onload=function(){ divId = document.getElementById("block1"); var height1 = images1.height;//图片的高度 var width1 = images1.width;//图片的宽度 v_left=(document.body.clientWidth-width1)/2; v_top=(document.body.clientHeight-height1)/2; divId.style.left=v_left; divId.style.top=v_top; } drag = 0; move = 0; // 拖拽对象 var ie = document.all; var nn6 = document.getElementById && !document.all; var isdrag = false; var y, x; var oDragObj; function moveMouse(e) { if (isdrag) { oDragObj.style.top = (nn6 ? nTY + e.clientY - y : nTY + event.clientY - y) + "px"; oDragObj.style.left = (nn6 ? nTX + e.clientX - x : nTX + event.clientX - x) + "px"; return false; } } // 拖拽方法 function initDrag(e) { var oDragHandle = nn6 ? e.target : event.srcElement; var topElement = "HTML"; while (oDragHandle.tagName != topElement && oDragHandle.className != "dragAble") { oDragHandle = nn6 ? oDragHandle.parentNode : oDragHandle.parentElement; } if (oDragHandle.className == "dragAble") { isdrag = true; oDragObj = oDragHandle; nTY = parseInt(oDragObj.style.top + 0); y = nn6 ? e.clientY : event.clientY; nTX = parseInt(oDragObj.style.left + 0); x = nn6 ? e.clientX : event.clientX; document.onmousemove = moveMouse; //document.onmouseup=MUp;// 事件会在鼠标按键被松开时发生 return false; } } document.onmousedown = initDrag; document.onmouseup = new Function("isdrag=false"); //上下左右移动 function clickMove(s) { if (s == "up") { dragObj.style.top = parseInt(dragObj.style.top) + 100; } else { if (s == "down") { dragObj.style.top = parseInt(dragObj.style.top) - 100; } else { if (s == "left") { dragObj.style.left = parseInt(dragObj.style.left) + 100; } else { if (s == "right") { dragObj.style.left = parseInt(dragObj.style.left) - 100; } } } } } //缩小倍数 function smallit() { //将图片缩小，失去热点 height1 = images1.height; width1 = images1.width; images1.height = height1 / 1.1; images1.width = width1 / 1.1; } //放大倍数 function bigit() { /*//将图片放大，不失热点 var zoom = parseInt(images1.style.zoom, 10) || 100; zoom += event.wheelDelta / 12; if (zoom > 0) { images1.style.zoom = (zoom+10) + "%"; }*/ //将图片放大，失去热点 height1 = images1.height; width1 = images1.width; images1.height = height1 * 1.1; images1.width = width1 * 1.1; } //还原 function realsize() { images1.style.zoom=100+"%"; images1.height = images2.height; images1.width = images2.width; divId.style.left=v_left; divId.style.top=v_top; } function featsize() { var width1 = images2.width; var height1 = images2.height; var width2 = 360; var height2 = 200; var h = height1 / height2; var w = width1 / width2; if (height1 < height2 && width1 < width2) { images1.height = height1; images1.width = width1; } else { if (h > w) { images1.height = height2; images1.width = width1 * height2 / height1; } else { images1.width = width2; images1.height = height1 * width2 / width1; } } block1.style.left = 0; block1.style.top = 0; } //鼠标滚轮放大缩小 function bbimg(o) { /*var eleLeft; var eleTop; if(document.documentElement){ eleLeft = document.documentElement.scrollLeft; eleTop = document.documentElement.scrollTop; } else{ eleLeft = document.body.scrollLeft; eleTop = document.body.scrollTop; } v_left+=eleLeft; v_top+=eleTop; //divId.style.left=v_left; //divId.style.top=v_top; alert(document.documentElement.scrollTop +"----xxx"+document.body.scrollTop+window.pageyoffset);*/ var zoom = parseInt(o.style.zoom, 10) || 100; zoom += event.wheelDelta / 12; if (zoom > 0) { o.style.zoom = zoom + "%"; } return false; }

希望本文所述对大家JavaScript程序设计有所帮助。