前端常用的JavaScript和jquery代码片段

// 数组排重
function getFilterArray (array) {
    const res = [];
    const json = {};
    for (let i = 0; i < array.length; i++){
        const _self = array[i];
        if(!json[_self]){
            res.push(_self);
            json[_self] = 1;
        }
    }
    return res;
}

 Object.defineProperty() //方法会直接在一个对象上定义一个新属性，或者修改一个对象的现有属性， 并返回这个对象。
  <div >
        <input type="text" >
        <p ></p>
    </div>
    <script>
        var obj = {}
        Object.defineProperty(obj, 'txt', {
            get: function () {
                return obj
            },
            set: function (newValue) {
                document.getElementById('txt').value = newValue
                document.getElementById('show-txt').innerHTML = newValue
            }
        })
        document.addEventListener('keyup', function (e) {
            obj.txt = e.target.value
        })
    </script>

$("a[href='#top']").click(function() {
  $("html, body").animate({ scrollTop: 0 }, "slow");
  return false;
});

 var handleGoTop = function () {
        var offset = 300;
        var duration = 500;

        if (navigator.userAgent.match(/iPhone|iPad|iPod/i)) {  // ios supported
            $(window).bind("touchend touchcancel touchleave", function(e){
               if ($(this).scrollTop() > offset) {
                    $('.scroll-to-top').fadeIn(duration);
                } else {
                    $('.scroll-to-top').fadeOut(duration);
                }
            });
        } else {  // general 
            $(window).scroll(function() {
                if ($(this).scrollTop() > offset) {
                    $('.scroll-to-top').fadeIn(duration);
                } else {
                    $('.scroll-to-top').fadeOut(duration);
                }
            });
        }
        
        $('.scroll-to-top').click(function(e) {
            e.preventDefault();
            $('html, body').animate({scrollTop: 0}, duration);
            return false;
        });
    };