這篇文章主要介紹了js拖拽一些常見的思路方法,需要的朋友可以參考下
js拖拽的常見思路 1.通過onmousedown,onmousemove,onmouseup分別模擬開始拖拽，拖拽中和拖拽結束時的事件（）。 如果手機的觸摸事件的話則分別是ontouchstart,ontouchmove和ontouchend。 2.鼠標按下即發生onmousedown事件時：獲取鼠標位置，獲取被拖動元素的位置，記錄兩者之間的縱橫坐標的差值（）。對document元素綁定onmousemove,onmouseup事件。 剛開始接觸js拖拽時，我當時疑惑的是為什麼是對document綁定而不是對被拖動的元素綁定呢？原來是如果對被拖動元素綁定的話當鼠標拖動過快時，會導致鼠標與被拖動元素的脫離。 3.鼠標拖動即發生onmousemove事件時：將被拖拽元素的position改成絕對位置，這個可以通過left和top改變該元素的位置，從而使得該元素隨著鼠標的拖拽而移動。獲取鼠標位置，將鼠標x坐標（e.clientX）減去第2步儲存的橫坐標差作為被拖動元素的left值，將鼠標x坐標（e.clientY）減去第2步儲存的縱坐標差作為被拖動元素的top值。實現元素跟隨鼠標拖動的效果。 4.鼠標按鍵彈起即發生onmouseup事件時：清空onmousemove和onmouseup事件 比較流行的拖拽插件dom-drag類庫（作者： Aaron Boodman） 其源代碼如下 代碼如下: /*其中( dom-drag.js )文件************************************************** * dom-drag.js * 09.25.2001 * www.youngpup.net ************************************************** * 10.28.2001 - fixed minor bug where events * sometimes fired off the handle, not the root. **************************************************/ var Drag = { obj : null, init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper) { o.onmousedown = Drag.start; o.hmode = bSwapHorzRef ? false : true ; o.vmode = bSwapVertRef ? false : true ; o.root = oRoot && oRoot != null ? oRoot : o ; if (o.hmode && isNaN(parseInt(o.root.style.left ))) o.root.style.left = "0px"; if (o.vmode && isNaN(parseInt(o.root.style.top ))) o.root.style.top = "0px"; if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right = "0px"; if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px"; o.minX = typeof minX != 'undefined' ? minX : null; o.minY = typeof minY != 'undefined' ? minY : null; o.maxX = typeof maxX != 'undefined' ? maxX : null; o.maxY = typeof maxY != 'undefined' ? maxY : null; o.xMapper = fXMapper ? fXMapper : null; o.yMapper = fYMapper ? fYMapper : null; o.root.onDragStart = new Function(); o.root.onDragEnd = new Function(); o.root.onDrag = new Function(); }, start : function(e) { var o = Drag.obj = this; e = Drag.fixE(e); var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom); var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right ); o.root.onDragStart(x, y); o.lastMouseX = e.clientX; o.lastMouseY = e.clientY; if (o.hmode) { if (o.minX != null) o.minMouseX = e.clientX - x + o.minX; if (o.maxX != null) o.maxMouseX = o.minMouseX + o.maxX - o.minX; } else { if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x; if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x; } if (o.vmode) { if (o.minY != null) o.minMouseY = e.clientY - y + o.minY; if (o.maxY != null) o.maxMouseY = o.minMouseY + o.maxY - o.minY; } else { if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y; if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y; } document.onmousemove = Drag.drag; document.onmouseup = Drag.end; return false; }, drag : function(e) { e = Drag.fixE(e); var o = Drag.obj; var ey = e.clientY; var ex = e.clientX; var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom); var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right ); var nx, ny; if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX); if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX); if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY); if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY); nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1)); ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1)); if (o.xMapper) nx = o.xMapper(y) else if (o.yMapper) ny = o.yMapper(x) Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px"; Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px"; Drag.obj.lastMouseX = ex; Drag.obj.lastMouseY = ey; Drag.obj.root.onDrag(nx, ny); return false; }, end : function() { document.onmousemove = null; document.onmouseup = null; Drag.obj.root.onDragEnd( parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]), parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"])); Drag.obj = null; }, fixE : function(e) { if (typeof e == 'undefined') e = window.event; if (typeof e.layerX == 'undefined') e.layerX = e.offsetX; if (typeof e.layerY == 'undefined') e.layerY = e.offsetY; return e; } }; 二：拖拽排序也是一種常見的效果 常見實現思路 1.將點擊進行拖拽的元素轉換為絕對路徑，同時新建一個臨時元素替代其所在的位置。 2.移動過程中通過循環計算鼠標與剩余元素的位置關系，如果鼠標位置處於該元素中時，在該元素的nextSibling前面插入第1步時創建的臨時元素； 3.結束時在臨時元素前面插入被拖拽元素，刪除臨時元素。 網上有個冷月無聲博主寫的挺好的，在此轉載一下其代碼 以下為其代碼 代碼如下: (function(win, doc){ var _this = null; var info = {}; var list = []; var Sortable = function(opts) { this.opts = opts; _this = this; list = X.getByClass(this.opts.sortClass, doc); X.addEvent(doc, 'mousedown', this.handleEvent); X.addEvent(doc, 'mousemove', this.handleEvent); X.addEvent(doc, 'mouseup', this.handleEvent); }; Sortable.prototype = { handleEvent: function(event) { var e = event || win.event; var target = event.target || event.srcElement; switch (event.type) { case 'mousedown': X.hasClass(target, _this.opts.sortClass) && _this.downEvent.call(_this, e, target); break; case 'mousemove': info.dObj && _this.moveEvent.call(_this, e, target); break; case 'mouseup': info.dObj && _this.upEvent.call(_this, e, target); break; default: break; } }, downEvent: function(e, target) { info.dObj = target; var off = X.getOffset(target); target.x = e.clientX - off[0]; target.y = e.clientY - off[1]; target.style.position = 'absolute'; target.style.left = off[0] +'px'; target.style.top = off[1] +'px'; info.vObj = doc.createElement('div'); info.vObj.style.width = off[2] +'px'; info.vObj.style.height = off[3] +'px'; target.parentNode.insertBefore(info.vObj, target); }, moveEvent: function(e, target) { win.getSelection ? win.getSelection().removeAllRanges() : doc.selection.empty(); info.dObj.style.left = e.clientX - info.dObj.x +'px'; info.dObj.style.top = e.clientY - info.dObj.y +'px'; for(var i = 0; i < list.length; i++) { if(list[i] === info.dObj) { continue; } var off = X.getOffset(list[i]); if(e.clientX > off[0] && e.clientX < off[0] + off[2] && e.clientY > off[1] && e.clientY < off[1] + off[3]) { switch (true) { case e.clientY < (off[1] + off[3]) / 2: list[i].parentNode.insertBefore(info.vObj, list[i]); break; case !list[i].nextSibling: list[i].parentNode.appendChild(info.vObj); break; default: list[i].parentNode.insertBefore(info.vObj, list[i].nextSibling); break; } } } }, upEvent: function(e, target) { info.dObj.style.position = 'static'; info.vObj.parentNode.insertBefore(info.dObj, info.vObj); info.dObj.parentNode.removeChild(info.vObj); info = {}; } }; win.Sortable = Sortable; })(window, document);