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1.1 说明
在项目过程中，有时候需要动态的去展示一些数据的加载状态，如一个数字为10000，需要5秒时间滚动加载完成。此时使用countup.js就能够很方便的处理此类功能问题。
1.2 countup.js
countup.js是一个无依赖性、轻量级的javascript类，可用于快速创建动画，以更有趣的方式显示数字/数据。详见countup.js
1.3 countup.js使用
npm install countup 进行安装依赖
import CountUp from "countup" 在页面中引入
new CountUp(target, startVal, endVal, decimals, duration, options)
参数：
target: 目标元素的id *必填
startVal：开始的值(从哪个值开始) *必填
endVal：结束的值(滚动到哪个值结束) *必填
decimals：小数位数，默认值为0 *可选
duration：动画持续时间，单位为秒，默认值为2 *可选
options：选项的可选对象 *可选
useEasing:true --是否使用缓动动画，默认为缓动，可设置为false让其匀速
useGrouping:true --对数字进行分组，如12345，按三位一组变为类似12,345这样的
separator: ',' --分组时使用的分隔符默认是逗号
decimal: '.' --小数点
prefix: '' --添加前缀如12345，变为￥12345
suffix: '' --添加后缀如12345 通过添加后缀变为12345$，12345元之类的
方法：
暂停/恢复 pauseResume
重置动画 reset
更新值 update(newVal)
2. 代码
2.1 源代码
var CountUp = function(target, startVal, endVal, decimals, duration, options) {
var self = this;
self.version = function() {
return "1.9.2"
};
self.options = {
useEasing: true,
useGrouping: true,
separator: ",",
decimal: ".",
easingFn: easeOutExpo,
formattingFn: formatNumber,
prefix: "",
suffix: "",
numerals: []
};
if (options && typeof options === "object") {
for (var key in self.options) {
if (options.hasOwnProperty(key) && options[key] !== null) {
self.options[key] = options[key]
}
}
}
if (self.options.separator === "") {
self.options.useGrouping = false
} else {
self.options.separator = "" + self.options.separator
}
var lastTime = 0;
var vendors = ["webkit", "moz", "ms", "o"];
for (var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
window.requestAnimationFrame = window[vendors[x] + "RequestAnimationFrame"];
window.cancelAnimationFrame = window[vendors[x] + "CancelAnimationFrame"] || window[vendors[x] + "CancelRequestAnimationFrame"]
}
if (!window.requestAnimationFrame) {
window.requestAnimationFrame = function(callback, element) {
var currTime = new Date().getTime();
var timeToCall = Math.max(0, 16 - (currTime - lastTime));
var id = window.setTimeout(function() {
callback(currTime + timeToCall)
},
timeToCall);
lastTime = currTime + timeToCall;
return id
}
}
if (!window.cancelAnimationFrame) {
window.cancelAnimationFrame = function(id) {
clearTimeout(id)
}
}
function formatNumber(num) {
num = num.toFixed(self.decimals);
num += "";
var x, x1, x2, x3, i, l;
x = num.split(".");
x1 = x[0];
x2 = x.length > 1 ? self.options.decimal + x[1] : "";
if (self.options.useGrouping) {
x3 = "";
for (i = 0, l = x1.length; i < l; ++i) {
if (i !== 0 && ((i % 3) === 0)) {
x3 = self.options.separator + x3
}
x3 = x1[l - i - 1] + x3
}
x1 = x3
}
if (self.options.numerals.length) {
x1 = x1.replace(/[0-9]/g,
function(w) {
return self.options.numerals[ + w]
});
x2 = x2.replace(/[0-9]/g,
function(w) {
return self.options.numerals[ + w]
})
}
return self.options.prefix + x1 + x2 + self.options.suffix
}
function easeOutExpo(t, b, c, d) {
return c * ( - Math.pow(2, -10 * t / d) + 1) * 1024 / 1023 + b
}
function ensureNumber(n) {
return (typeof n === "number" && !isNaN(n))
}
self.initialize = function() {
if (self.initialized) {
return true
}
self.error = "";
self.d = (typeof target === "string") ? document.getElementById(target) : target;
if (!self.d) {
self.error = "[CountUp] target is null or undefined";
return false
}
self.startVal = Number(startVal);
self.endVal = Number(endVal);
if (ensureNumber(self.startVal) && ensureNumber(self.endVal)) {
self.decimals = Math.max(0, decimals || 0);
self.dec = Math.pow(10, self.decimals);
self.duration = Number(duration) * 1000 || 2000;
self.countDown = (self.startVal > self.endVal);
self.frameVal = self.startVal;
self.initialized = true;
return true
} else {
self.error = "[CountUp] startVal (" + startVal + ") or endVal (" + endVal + ") is not a number";
return false
}
};
self.printValue = function(value) {
var result = self.options.formattingFn(value);
if (self.d.tagName === "INPUT") {
this.d.value = result
} else {
if (self.d.tagName === "text" || self.d.tagName === "tspan") {
this.d.textContent = result
} else {
this.d.innerHTML = result
}
}
};
self.count = function(timestamp) {
if (!self.startTime) {
self.startTime = timestamp
}
self.timestamp = timestamp;
var progress = timestamp - self.startTime;
self.remaining = self.duration - progress;
if (self.options.useEasing) {
if (self.countDown) {
self.frameVal = self.startVal - self.options.easingFn(progress, 0, self.startVal - self.endVal, self.duration)
} else {
self.frameVal = self.options.easingFn(progress, self.startVal, self.endVal - self.startVal, self.duration)
}
} else {
if (self.countDown) {
self.frameVal = self.startVal - ((self.startVal - self.endVal) * (progress / self.duration))
} else {
self.frameVal = self.startVal + (self.endVal - self.startVal) * (progress / self.duration)
}
}
if (self.countDown) {
self.frameVal = (self.frameVal < self.endVal) ? self.endVal: self.frameVal
} else {
self.frameVal = (self.frameVal > self.endVal) ? self.endVal: self.frameVal
}
self.frameVal = Math.round(self.frameVal * self.dec) / self.dec;
self.printValue(self.frameVal);
if (progress < self.duration) {
self.rAF = requestAnimationFrame(self.count)
} else {
if (self.callback) {
self.callback()
}
}
};
self.start = function(callback) {
if (!self.initialize()) {
return
}
self.callback = callback;
self.rAF = requestAnimationFrame(self.count)
};
self.pauseResume = function() {
if (!self.paused) {
self.paused = true;
cancelAnimationFrame(self.rAF)
} else {
self.paused = false;
delete self.startTime;
self.duration = self.remaining;
self.startVal = self.frameVal;
requestAnimationFrame(self.count)
}
};
self.reset = function() {
self.paused = false;
delete self.startTime;
self.initialized = false;
if (self.initialize()) {
cancelAnimationFrame(self.rAF);
self.printValue(self.startVal)
}
};
self.update = function(newEndVal) {
if (!self.initialize()) {
return
}
newEndVal = Number(newEndVal);
if (!ensureNumber(newEndVal)) {
self.error = "[CountUp] update() - new endVal is not a number: " + newEndVal;
return
}
self.error = "";
if (newEndVal === self.frameVal) {
return
}
cancelAnimationFrame(self.rAF);
self.paused = false;
delete self.startTime;
self.startVal = self.frameVal;
self.endVal = newEndVal;
self.countDown = (self.startVal > self.endVal);
self.rAF = requestAnimationFrame(self.count)
};
if (self.initialize()) {
self.printValue(self.startVal)
}
};2.1 代码示例
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