多次包含倒数计时器

Question

我找到了这个倒数计时器，我想将它包含在我的一个模块中。不幸的是，我无法弄清楚如何在一个页面上多次使用计时器（经典的 - 只有最后一个计时器正在运行） - 我也知道可能（？）go函数应该是原因 - 但目前我可以'不知道如何实例化计时器。

到目前为止我所拥有的（但它不起作用）：

Codepen 原文：https://codepen.io/l422y/pen/cdwhm

我有深入的 JS 基础知识，但这仍然超出了我的视野。

var ringer = {
  //countdown_to: "10/31/2014",
  //countdown_to: targetdaytime,
  rings: {
    'DAYS': {
      s: 86400000, // mseconds in a day,
      max: 365
    },
    'HOURS': {
      s: 3600000, // mseconds per hour,
      max: 24
    },
    'MINUTES': {
      s: 60000, // mseconds per minute
      max: 60
    },
    'SECONDS': {
      s: 1000,
      max: 60
    },
    'MICROSEC': {
      s: 10,
      max: 100
    }
  },
  r_count: 5,
  r_spacing: 10, // px
  r_size: 100, // px
  r_thickness: 2, // px
  update_interval: 11, // ms


  init: function(container, targetdaytime) {

    $r = ringer;
    $r.cvs = document.createElement('canvas');

    $r.size = {
      w: ($r.r_size + $r.r_thickness) * $r.r_count + ($r.r_spacing * ($r.r_count - 1)),
      h: ($r.r_size + $r.r_thickness)
    };

    $r.cvs.setAttribute('width', $r.size.w);
    $r.cvs.setAttribute('height', $r.size.h);
    $r.ctx = $r.cvs.getContext('2d');
    $(container).append($r.cvs);
    $r.cvs = $($r.cvs);
    $r.ctx.textAlign = 'center';
    $r.actual_size = $r.r_size + $r.r_thickness;
    $r.countdown_to_time = new Date(targetdaytime).getTime();
    $r.cvs.css({
      width: $r.size.w + "px",
      height: $r.size.h + "px"
    });
    $r.go();
  },
  ctx: null,
  go: function() {
    var idx = 0;

    $r.time = (new Date().getTime()) - $r.countdown_to_time;


    for (var r_key in $r.rings) $r.unit(idx++, r_key, $r.rings[r_key]);

    setTimeout($r.go, $r.update_interval);
  },
  unit: function(idx, label, ring) {
    var x, y, value, ring_secs = ring.s;
    value = parseFloat($r.time / ring_secs);
    $r.time -= Math.round(parseInt(value)) * ring_secs;
    value = Math.abs(value);

    x = ($r.r_size * .5 + $r.r_thickness * .5);
    x += +(idx * ($r.r_size + $r.r_spacing + $r.r_thickness));
    y = $r.r_size * .5;
    y += $r.r_thickness * .5;


    // calculate arc end angle
    var degrees = 360 - (value / ring.max) * 360.0;
    var endAngle = degrees * (Math.PI / 180);

    $r.ctx.save();

    $r.ctx.translate(x, y);
    $r.ctx.clearRect($r.actual_size * -0.5, $r.actual_size * -0.5, $r.actual_size, $r.actual_size);

    // first circle
    $r.ctx.strokeStyle = "rgba(128,128,128,0.2)";
    $r.ctx.beginPath();
    $r.ctx.arc(0, 0, $r.r_size / 2, 0, 2 * Math.PI, 2);
    $r.ctx.lineWidth = $r.r_thickness;
    $r.ctx.stroke();

    // second circle
    $r.ctx.strokeStyle = "rgba(253, 128, 1, 0.9)";
    $r.ctx.beginPath();
    $r.ctx.arc(0, 0, $r.r_size / 2, 0, endAngle, 1);
    $r.ctx.lineWidth = $r.r_thickness;
    $r.ctx.stroke();

    // label
    $r.ctx.fillStyle = "#ffffff";

    $r.ctx.font = '12px Helvetica';
    $r.ctx.fillText(label, 0, 23);
    $r.ctx.fillText(label, 0, 23);

    $r.ctx.font = 'bold 40px Helvetica';
    $r.ctx.fillText(Math.floor(value), 0, 10);

    $r.ctx.restore();
  }
}

jQuery(document).ready(function($) {
  new ringer.init('#cd-container-1', '12/24/2020');
  new ringer.init('#cd-container-2', '10/31/2020');
});

body,
html {
  width: 100%;
  height: 100%;
  margin: 0;
}

html {
  display: table;
}

canvas {
  width: 900px;
  height: 200px;
  display: block;
  position: relative;
  background: transparent;
  margin: 40px auto;
}

body {
  background: #000000;
  background-image: url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/12399/free-pumpkin-wallpaper-25771-26455-hd-wallpapers.jpg");
  background-position: top center;
  background-size: cover;
  color: #fff;
  margin: 0;
  padding: 0;
  overflow: hidden;
  display: table-cell;
  vertical-align: middle;
  text-align: center;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="cd-container-1"></div>
<div id="cd-container-2"></div>

Answer 1

这是因为你的对象不是 JS 类，所以不能创建它的实例。它基本上是一个类的单个实例。

我为你把它变成了一个类，所以现在你可以初始化它的多个实例：

class Ringer { // <-- make class from it
  rings = { // <-- object properties to class fields
    'DAYS': {
      s: 86400000, // mseconds in a day,
      max: 365
    },
    'HOURS': {
      s: 3600000, // mseconds per hour,
      max: 24
    },
    'MINUTES': {
      s: 60000, // mseconds per minute
      max: 60
    },
    'SECONDS': {
      s: 1000,
      max: 60
    },
    'MICROSEC': {
      s: 10,
      max: 100
    }
  };
  r_count = 5;
  r_spacing = 10; // px
  r_size = 100; // px
  r_thickness = 2; // px
  update_interval = 11; // ms
  ctx = null; 


  init (container, targetdaytime) { // <-- functions to class methods

    this.cvs = document.createElement('canvas'); // <-- just access this instead of reference to the object

    this.size = {
      w: (this.r_size + this.r_thickness) * this.r_count + (this.r_spacing * (this.r_count - 1)),
      h: (this.r_size + this.r_thickness)
    };

    this.cvs.setAttribute('width', this.size.w);
    this.cvs.setAttribute('height', this.size.h);
    this.ctx = this.cvs.getContext('2d');
    $(container).append(this.cvs);
    this.cvs = $(this.cvs);
    this.ctx.textAlign = 'center';
    this.actual_size = this.r_size + this.r_thickness;
    this.countdown_to_time = new Date(targetdaytime).getTime();
    this.cvs.css({
      width: this.size.w + "px",
      height: this.size.h + "px"
    });
    this.go();
  }
  
  go() {
    var idx = 0;

    this.time = (new Date().getTime()) - this.countdown_to_time;
    
    for (var r_key in this.rings) this.unit(idx++, r_key, this.rings[r_key]);

    setTimeout(() => this.go(), this.update_interval); // () => this.go() instead of $r.go
  }
  
  unit(idx, label, ring) {
    var x, y, value, ring_secs = ring.s;
    value = parseFloat(this.time / ring_secs);
    this.time -= Math.round(parseInt(value)) * ring_secs;
    value = Math.abs(value);

    x = (this.r_size * .5 + this.r_thickness * .5);
    x += +(idx * (this.r_size + this.r_spacing + this.r_thickness));
    y = this.r_size * .5;
    y += this.r_thickness * .5;


    // calculate arc end angle
    var degrees = 360 - (value / ring.max) * 360.0;
    var endAngle = degrees * (Math.PI / 180);

    this.ctx.save();

    this.ctx.translate(x, y);
    this.ctx.clearRect(this.actual_size * -0.5, this.actual_size * -0.5, this.actual_size, this.actual_size);

    // first circle
    this.ctx.strokeStyle = "rgba(128,128,128,0.2)";
    this.ctx.beginPath();
    this.ctx.arc(0, 0, this.r_size / 2, 0, 2 * Math.PI, 2);
    this.ctx.lineWidth = this.r_thickness;
    this.ctx.stroke();

    // second circle
    this.ctx.strokeStyle = "rgba(253, 128, 1, 0.9)";
    this.ctx.beginPath();
    this.ctx.arc(0, 0, this.r_size / 2, 0, endAngle, 1);
    this.ctx.lineWidth = this.r_thickness;
    this.ctx.stroke();

    // label
    this.ctx.fillStyle = "#ffffff";

    this.ctx.font = '12px Helvetica';
    this.ctx.fillText(label, 0, 23);
    this.ctx.fillText(label, 0, 23);

    this.ctx.font = 'bold 40px Helvetica';
    this.ctx.fillText(Math.floor(value), 0, 10);

    this.ctx.restore();
  }
}

jQuery(document).ready(function($) {
  (new Ringer()).init('#cd-container-1', '12/24/2020'); // <-- init new instance with new Ringer() and call init() on that instance
  (new Ringer()).init('#cd-container-2', '10/31/2020');
});

body,
html {
  width: 100%;
  height: 100%;
  margin: 0;
}

html {
  display: table;
}

canvas {
  width: 900px;
  height: 200px;
  display: block;
  position: relative;
  background: transparent;
  margin: 40px auto;
}

body {
  background: #000000;
  background-image: url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/12399/free-pumpkin-wallpaper-25771-26455-hd-wallpapers.jpg");
  background-position: top center;
  background-size: cover;
  color: #fff;
  margin: 0;
  padding: 0;
  overflow: hidden;
  display: table-cell;
  vertical-align: middle;
  text-align: center;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="cd-container-1"></div>
<div id="cd-container-2"></div>

如果您想了解更多关于类及其工作原理的信息，我在这里找到了一个很酷的小总结：https://www.digitalocean.com/community/tutorials/js-objects-prototypes-classes

Answer 2

简单：将其包装在一个函数中。

function createRinger() {
    const ringer = { ... }
    return ringer
}

const ringer1 = createRinger()
const ringer2 = createRinger()

ringer1.init(target1, targetDateTime1)
ringer2.init(target2, targetDateTime2)

还有其他方法可以提高内存使用效率（例如使用原型链），但除非您在页面上有很多计时器，否则这些方法没有实际意义。