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一些常用的JS函数

时间:2015-06-09 编辑:bluthly 来源:本站整理

//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;

        }

    }

}

关键词:常用 JS 函数