一些常用的JS函数
//获取元素属性
function getStyle(obj, attr) {
return obj.currentStyle ? obj.currentStyle[attr] : getComputedStyle(obj, 0)[attr];
}
//运动函数
function doMove(obj, attr, speed, target, endFn) {
clearInterval(obj.timer);
speed = parseInt(getStyle(obj, attr)) < target ? speed : -speed;
//alert(speed);
obj.timer = setInterval(function () {
var curPosition = parseInt(getStyle(obj, attr)) + speed;
if (curPosition > target && speed > 0 || curPosition < target && speed < 0)
curPosition = target;
obj.style[attr] = curPosition + 'px';
if (curPosition == target) {
clearInterval(obj.timer);
endFn && endFn();
} }, 50); }
//抖动函数
//透明度渐变函数
//需找与数组相等的值函数
function arrIndexOf(arr, v) {
for (i = 0; i < arr.length; i++) {
if (arr[i] == v) {
return i; //返回与目标值相等的数组的下标值
}
}
return -1;
}
//getElementByClassName函数
function getElementByClassName(parent, tagName, className) {
var aEls = parent.getElementsByTagName(tagName);
var arr = [];
for (var i = 0; i < aEls.length; i++) {
var arrClassName = aEls[i].className.split(' ');
var _index = arrIndexOf(arrClassName, className);
if (_index != -1) {
arr.push(aEls[i]);
}
}
return arr;
}
//addClass函数
function addClass(obj, className) {
if (obj.className == '') {
//如果原来没有class
obj.className = className;
}
else {
var arrClassName = obj.className.split(' ');
var _index = arrIndexOf(arrClassName, className);
if (_index == -1) {
//如果要添加的class在原来的class中不存在
obj.className += ' ' + className;
}
//如果要添加的class在原来的class中存在,则不需要做任何事
}
}
//removeClass函数
function removeClass(obj, className) {
//如果原来有class
if (obj.className != '') {
var arrClassName = obj.className.split(' ');
var _index = arrIndexOf(arrClassName, className);
if (_index != -1) {
arrClassName.splice(_index, 1); //删除需要删除的calss
obj.className = arrClassName.join(' '); //然后将arrClassName数组拼接起来
}
}
}
//绑定事件函数
function bind(obj, evname, fn) {
if (obj.addEventListener) {
obj.addEventListener(evname, fn, false);
} else {
obj.attachEvent('on' + evname, function () {
fn.call(obj); //fn()==fn.call() call(第一个参数,第二个参数) call函数可以改变函数this的指向,call函数传入的第一个参数就是改变this指向的值,call的第二第三个参数就是原函数的参数
});
}
}
//鼠标在可视区域内的拖拽 不兼容非标准IE
function clientDrag(obj) {
obj.onmousedown = function (ev) {
ev = ev || event;
var ms_b = ev.clientX - obj.offsetLeft;
var ms_t = ev.clientY - obj.offsetTop;
document.onmousemove = function (ev) {
ev = ev || event;
var currX = ev.clientX - ms_b;
var currY = ev.clientY - ms_t;
var Width = document.body.clientWidth || document.documentElement.cilentWidth;
var Height = document.body.clientHeight || document.documentElement.cilentHeight;
if (currX < 0) { currX = 0; }
else if (currX > Width - obj.clientWidth) {
currX = Width - obj.clientWidth;
}
if (currY < 0) { currY = 0; }
else if (currY > Height - obj.clientHeight) {
currY = Height - obj.clientHeight;
}
obj.style.left = currX + 'px';
obj.style.top = currY + 'px';
return false;
}
document.onmouseup = function () {
document.onmousemove = document.onmouseup = null;
}
}
}