瀏覽器兼容設置 + 拖拽封裝

瀏覽器兼容設置

都以點擊事件 onclick 爲例：javascript

事件對象獲取

document.onclick = function(ev) {
        let e = ev || window.event;
}

獲取鍵碼

let w = e.which || e.keyCode;

目標對象 / 觸發對象

button.onclick = function() {
	let target = e.target || window.event.srcElement;
}

阻止超連接默認行爲的函數

e 爲獲取到的事件java

function preDef(e) {
	if(e.preventDefault) {
		e.preventDefault();
	} else {
		window.event.returnValue = false;
	}
}

事件監聽器

function addEvent(node,evenType,funName) {
    if(node.addEventListener) {
        node.addEventListener(evenType, funName,false);
    } else {
        node.attachEvent('on' + evenType, funName);
    }
}

function removeEvent(node,evenType,funName) {
    if(node.removeEventListener) {
        node.removeEventListener(evenType, funName,false);
    } else {
        node.detachEvent('on' + evenType, funName);
    }
}

獲取當前窗口的寬高

let Width = document.documentElement.clientWidth || document.body.clientWidth;
let Height = document.documentElement.clientHeight || document.body.clientHeight;

拖拽封裝

普通拖拽封裝

function drag(node) {
    node.onmousedown = function(ev) {
        let e = ev || window.event;

        // 獲取鼠標到 node 左上角的相對位置
        let offSetX = e.clientX - node.offsetLeft;
        let offSetY = e.clientY - node.offsetTop;

        // 鼠標移動時，計算 node 左上角應該在的位置
        document.onmousemove = function(ev) {
            let e = ev || window.event;
            node.style.left = e.clientX - offSetX + 'px';
            node.style.top = e.clientY - offSetY + 'px';
        }
    }

    document.onmouseup = function() {
        document.onmousemove = null;
    }
}

限制出界的拖拽封裝

function limitDrag(node) {
    node.onmousedown = function (ev) {
        let e = ev || window.event;

        // 獲取鼠標到 node 左上角的相對位置
        let offSetX = e.clientX - node.offsetLeft;
        let offSetY = e.clientY - node.offsetTop;
   
        document.onmousemove = function (ev) {
            let e = ev || window.event;
            // 鼠標移動時，計算 node 左上角應該在的位置
            let x = e.clientX - offSetX;
            let y = e.clientY - offSetY;

            // 限制出界
            // 獲取當前窗口的寬高
            let Width = document.documentElement.clientWidth || document.body.clientWidth;
            let Height = document.documentElement.clientHeight || document.body.clientHeight;
            if (x <= 0) {
                x = 0;
            }
            if (x >= Width - node.offsetWidth) {
                x = Width - node.offsetWidth
            }
            if (y <= 0) {
                y = 0;
            }
            if (y >= Height - node.offsetHeight) {
                y = Height - node.offsetHeight
            }
            node.style.left = x + 'px';
            node.style.top = y + 'px';
        }
    }

    document.onmouseup = function () {
        document.onmousemove = null;
    }
}

針對拖拽封裝的小栗子：
https://blog.csdn.net/Web_blingbling/article/details/107868162
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