// 为element增加一个样式名为newClassName的新样式

function addClass(element, newClassName) {
    var value = element.className;
        element.className = value + " " + newClassName;
}
var box = document.getElementById("box");
addClass(box,'js')

 

// 移除element中的样式oldClassName

function removeClass(element, oldClassName) {
   var value = element.className;
   var str = value.replace(oldClassName,"");
   element.className = str;
}
var box = document.getElementById("box");
console.log(removeClass(box,"active"));

 

// 判断siblingNode和element是否为同一个父元素下的同一级的元素,返回bool值

function isSiblingNode(element, siblingNode) {
    return element.parentNode===siblingNode.parentNode;
}

var box1 = document.getElementById("box1");
var box2 = document.getElementById("box2");

console.log(isSiblingNode(box1,box2))

 

// 获取element相对于浏览器窗口的位置,返回一个对象{x, y}

function getPosition(element) {
    return {
        x:element.offsetLeft,
        y:element.offsetTop
    };
}
var box1 = document.getElementById("box1");
console.log(getPosition(box1));