48 lines
1.4 KiB
JavaScript
48 lines
1.4 KiB
JavaScript
/**
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* @desc scroll滚动方法
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|*| * scrollApi.getScrollTop()
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|*| * scrollApi.setScrollTop(h)
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|*| * scrollApi.scrollTo(to,duration)
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*/
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var requestAnimationFrame = function () {
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return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function (callback) {
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window.setTimeout(callback, 1000 / 60);
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};
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}();
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var scrollApi = {
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getScrollTop: function getScrollTop() {
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return document.documentElement && document.documentElement.scrollTop || document.body.scrollTop;
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},
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setScrollTop: function setScrollTop(h) {
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h && window.scrollTo(0, h);
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},
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scrollTo: function scrollTo(to) {
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var _this = this;
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var duration = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : 0;
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var minDecelerate = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 4;
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var diff = to - this.getScrollTop();
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if (diff === 0) return;
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if (duration <= 0) {
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this.setScrollTop(to);
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return;
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}
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var step = diff / duration * 10;
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requestAnimationFrame(function () {
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if (Math.abs(step) > Math.abs(diff)) {
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_this.setScrollTop(_this.getScrollTop() + diff);
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return;
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}
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_this.setScrollTop(_this.getScrollTop() + step);
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if (diff > 0 && _this.getScrollTop() >= to || diff < 0 && _this.getScrollTop() <= to) {
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return;
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}
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_this.scrollTo(to, duration - 16 / minDecelerate);
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});
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}
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};
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module.exports = scrollApi; |