Add Loader in page for download reqest

AddLoader.js

// js

xhr: function()
                            {
                                var xhr = new window.XMLHttpRequest();
                                let duration_change = true;
                                //Download progress
                                xhr.addEventListener("progress", function(evt){
                                    if (evt.lengthComputable) {
                                        var percentComplete = evt.loaded / evt.total;
                                        //Do something with download progress
                                        if (duration_change) {
                                            progress_circle.circleProgress('duration', 100);
                                            duration_change = false;
                                        }
                                        $('.progress-bar-info').text('We are almost there.');
                                        let percentage_to_show = 0.8 + percentComplete * 0.2;
                                        // console.log(percentage_to_show);

                                        progress_circle.circleProgress('value', percentage_to_show).on('circle-animation-progress', function(event, progress) {
                                            $(this).find('strong').html(Math.round(percentage_to_show * 100 ) + '<i>%</i>');
                                        });
                                    }
                                }, false);
                                return xhr;
                            },
								
								
								
								
// php
								
			return $dataTables->withHeaders(['Content-Length' => strlen($dataTables->getContent())]);


// inital load
 function progress_bar_start() {
                    console.log(calculated_estimated_time,total_cross_time);

                    progress_circle.circleProgress({
                        value: 0.8,
                        animation: {
                            duration: calculated_estimated_time,
                            easing: 'circleProgressEasing'
                        },
                    }).on('circle-animation-progress', function(event, progress) {
                        $(this).find('strong').html(Math.round(80 * progress) + '<i>%</i>');
                    });
                }

                progress_bar_start();


// library 


/**
 * jquery-circle-progress - jQuery Plugin to draw animated circular progress bars:
 * {@link http://kottenator.github.io/jquery-circle-progress/}
 *
 * @author Rostyslav Bryzgunov <[email protected]>
 * @version 1.2.2
 * @licence MIT
 * @preserve
 */
// UMD factory - https://github.com/umdjs/umd/blob/d31bb6ee7098715e019f52bdfe27b3e4bfd2b97e/templates/jqueryPlugin.js
// Uses AMD, CommonJS or browser globals to create a jQuery plugin.
(function(factory) {
  if (typeof define === 'function' && define.amd) {
    // AMD - register as an anonymous module
    define(['jquery'], factory);
  } else if (typeof module === 'object' && module.exports) {
    // Node/CommonJS
    var $ = require('jquery');
    factory($);
    module.exports = $;
  } else {
    // Browser globals
    factory(jQuery);
  }
})(function($) {
  /**
   * Inner implementation of the circle progress bar.
   * The class is not exposed _yet_ but you can create an instance through jQuery method call.
   *
   * @param {object} config - You can customize any class member (property or method).
   * @class
   * @alias CircleProgress
   */
  function CircleProgress(config) {
    this.init(config);
  }

  CircleProgress.prototype = {
    //--------------------------------------- public options ---------------------------------------
    /**
     * This is the only required option. It should be from `0.0` to `1.0`.
     * @type {number}
     * @default 0.0
     */
    value: 0.0,

    /**
     * Size of the canvas in pixels.
     * It's a square so we need only one dimension.
     * @type {number}
     * @default 100.0
     */
    size: 100.0,

    /**
     * Initial angle for `0.0` value in radians.
     * @type {number}
     * @default -Math.PI
     */
    startAngle: -Math.PI,

    /**
     * Width of the arc in pixels.
     * If it's `'auto'` - the value is calculated as `[this.size]{@link CircleProgress#size} / 14`.
     * @type {number|string}
     * @default 'auto'
     */
    thickness: 'auto',

    /**
     * Fill of the arc. You may set it to:
     *
     *   - solid color:
     *     - `'#3aeabb'`
     *     - `{ color: '#3aeabb' }`
     *     - `{ color: 'rgba(255, 255, 255, .3)' }`
     *   - linear gradient _(left to right)_:
     *     - `{ gradient: ['#3aeabb', '#fdd250'], gradientAngle: Math.PI / 4 }`
     *     - `{ gradient: ['red', 'green', 'blue'], gradientDirection: [x0, y0, x1, y1] }`
     *     - `{ gradient: [["red", .2], ["green", .3], ["blue", .8]] }`
     *   - image:
     *     - `{ image: 'http://i.imgur.com/pT0i89v.png' }`
     *     - `{ image: imageObject }`
     *     - `{ color: 'lime', image: 'http://i.imgur.com/pT0i89v.png' }` -
     *       color displayed until the image is loaded
     *
     * @default {gradient: ['#3aeabb', '#fdd250']}
     */
    fill: {
      gradient: ['#3aeabb', '#fdd250']
    },

    /**
     * Color of the "empty" arc. Only a color fill supported by now.
     * @type {string}
     * @default 'rgba(0, 0, 0, .1)'
     */
    emptyFill: 'rgba(0, 0, 0, .1)',

    /**
     * jQuery Animation config.
     * You can pass `false` to disable the animation.
     * @see http://api.jquery.com/animate/
     * @type {object|boolean}
     * @default {duration: 1200, easing: 'circleProgressEasing'}
     */
    animation: {
      duration: 1200,
      easing: 'circleProgressEasing'
    },

    /**
     * Default animation starts at `0.0` and ends at specified `value`. Let's call this _direct animation_.
     * If you want to make _reversed animation_ - set `animationStartValue: 1.0`.
     * Also you may specify any other value from `0.0` to `1.0`.
     * @type {number}
     * @default 0.0
     */
    animationStartValue: 0.0,

    /**
     * Reverse animation and arc draw.
     * By default, the arc is filled from `0.0` to `value`, _clockwise_.
     * With `reverse: true` the arc is filled from `1.0` to `value`, _counter-clockwise_.
     * @type {boolean}
     * @default false
     */
    reverse: false,

    /**
     * Arc line cap: `'butt'`, `'round'` or `'square'` -
     * [read more]{@link https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D.lineCap}.
     * @type {string}
     * @default 'butt'
     */
    lineCap: 'butt',

    /**
     * Canvas insertion mode: append or prepend it into the parent element?
     * @type {string}
     * @default 'prepend'
     */
    insertMode: 'prepend',

    //------------------------------ protected properties and methods ------------------------------
    /**
     * Link to {@link CircleProgress} constructor.
     * @protected
     */
    constructor: CircleProgress,

    /**
     * Container element. Should be passed into constructor config.
     * @protected
     * @type {jQuery}
     */
    el: null,

    /**
     * Canvas element. Automatically generated and prepended to [this.el]{@link CircleProgress#el}.
     * @protected
     * @type {HTMLCanvasElement}
     */
    canvas: null,

    /**
     * 2D-context of [this.canvas]{@link CircleProgress#canvas}.
     * @protected
     * @type {CanvasRenderingContext2D}
     */
    ctx: null,

    /**
     * Radius of the outer circle. Automatically calculated as `[this.size]{@link CircleProgress#size} / 2`.
     * @protected
     * @type {number}
     */
    radius: 0.0,

    /**
     * Fill of the main arc. Automatically calculated, depending on [this.fill]{@link CircleProgress#fill} option.
     * @protected
     * @type {string|CanvasGradient|CanvasPattern}
     */
    arcFill: null,

    /**
     * Last rendered frame value.
     * @protected
     * @type {number}
     */
    lastFrameValue: 0.0,

    /**
     * Init/re-init the widget.
     *
     * Throws a jQuery event:
     *
     * - `circle-inited(jqEvent)`
     *
     * @param {object} config - You can customize any class member (property or method).
     */
    init: function(config) {
      $.extend(this, config);
      this.radius = this.size / 2;
      this.initWidget();
      this.initFill();
      this.draw();
      // this.el.trigger('circle-inited');
    },

    /**
     * Initialize `<canvas>`.
     * @protected
     */
    initWidget: function() {
      if (!this.canvas)
        this.canvas = $('<canvas>')[this.insertMode == 'prepend' ? 'prependTo' : 'appendTo'](this.el)[0];

      var canvas = this.canvas;
      canvas.width = this.size;
      canvas.height = this.size;
      this.ctx = canvas.getContext('2d');

      if (window.devicePixelRatio > 1) {
        var scaleBy = window.devicePixelRatio;
        canvas.style.width = canvas.style.height = this.size + 'px';
        canvas.width = canvas.height = this.size * scaleBy;
        this.ctx.scale(scaleBy, scaleBy);
      }
    },

    /**
     * This method sets [this.arcFill]{@link CircleProgress#arcFill}.
     * It could do this async (on image load).
     * @protected
     */
    initFill: function() {
      var self = this,
        fill = this.fill,
        ctx = this.ctx,
        size = this.size;

      if (!fill)
        throw Error("The fill is not specified!");

      if (typeof fill == 'string')
        fill = {color: fill};

      if (fill.color)
        this.arcFill = fill.color;

      if (fill.gradient) {
        var gr = fill.gradient;

        if (gr.length == 1) {
          this.arcFill = gr[0];
        } else if (gr.length > 1) {
          var ga = fill.gradientAngle || 0, // gradient direction angle; 0 by default
            gd = fill.gradientDirection || [
                size / 2 * (1 - Math.cos(ga)), // x0
                size / 2 * (1 + Math.sin(ga)), // y0
                size / 2 * (1 + Math.cos(ga)), // x1
                size / 2 * (1 - Math.sin(ga))  // y1
              ];

          var lg = ctx.createLinearGradient.apply(ctx, gd);

          for (var i = 0; i < gr.length; i++) {
            var color = gr[i],
              pos = i / (gr.length - 1);

            if ($.isArray(color)) {
              pos = color[1];
              color = color[0];
            }

            lg.addColorStop(pos, color);
          }

          this.arcFill = lg;
        }
      }

      if (fill.image) {
        var img;

        if (fill.image instanceof Image) {
          img = fill.image;
        } else {
          img = new Image();
          img.src = fill.image;
        }

        if (img.complete)
          setImageFill();
        else
          img.onload = setImageFill;
      }

      function setImageFill() {
        var bg = $('<canvas>')[0];
        bg.width = self.size;
        bg.height = self.size;
        bg.getContext('2d').drawImage(img, 0, 0, size, size);
        self.arcFill = self.ctx.createPattern(bg, 'no-repeat');
        self.drawFrame(self.lastFrameValue);
      }
    },

    /**
     * Draw the circle.
     * @protected
     */
    draw: function() {
      if (this.animation)
        this.drawAnimated(this.value);
      else
        this.drawFrame(this.value);
    },

    /**
     * Draw a single animation frame.
     * @protected
     * @param {number} v - Frame value.
     */
    drawFrame: function(v) {
      this.lastFrameValue = v;
      this.ctx.clearRect(0, 0, this.size, this.size);
      this.drawEmptyArc(v);
      this.drawArc(v);
    },

    /**
     * Draw the arc (part of the circle).
     * @protected
     * @param {number} v - Frame value.
     */
    drawArc: function(v) {
      if (v === 0)
        return;

      var ctx = this.ctx,
        r = this.radius,
        t = this.getThickness(),
        a = this.startAngle;

      ctx.save();
      ctx.beginPath();

      if (!this.reverse) {
        ctx.arc(r, r, r - t / 2, a, a + Math.PI * 2 * v);
      } else {
        ctx.arc(r, r, r - t / 2, a - Math.PI * 2 * v, a);
      }

      ctx.lineWidth = t;
      ctx.lineCap = this.lineCap;
      ctx.strokeStyle = this.arcFill;
      ctx.stroke();
      ctx.restore();
    },

    /**
     * Draw the _empty (background)_ arc (part of the circle).
     * @protected
     * @param {number} v - Frame value.
     */
    drawEmptyArc: function(v) {
      var ctx = this.ctx,
        r = this.radius,
        t = this.getThickness(),
        a = this.startAngle;

      if (v < 1) {
        ctx.save();
        ctx.beginPath();

        if (v <= 0) {
          ctx.arc(r, r, r - t / 2, 0, Math.PI * 2);
        } else {
          if (!this.reverse) {
            ctx.arc(r, r, r - t / 2, a + Math.PI * 2 * v, a);
          } else {
            ctx.arc(r, r, r - t / 2, a, a - Math.PI * 2 * v);
          }
        }

        ctx.lineWidth = t;
        ctx.strokeStyle = this.emptyFill;
        ctx.stroke();
        ctx.restore();
      }
    },

    /**
     * Animate the progress bar.
     *
     * Throws 3 jQuery events:
     *
     * - `circle-animation-start(jqEvent)`
     * - `circle-animation-progress(jqEvent, animationProgress, stepValue)` - multiple event
     *   animationProgress: from `0.0` to `1.0`; stepValue: from `0.0` to `value`
     * - `circle-animation-end(jqEvent)`
     *
     * @protected
     * @param {number} v - Final value.
     */
    drawAnimated: function(v) {
      var self = this,
        el = this.el,
        canvas = $(this.canvas);

      // stop previous animation before new "start" event is triggered
      canvas.stop(true, false);
      el.trigger('circle-animation-start');

      canvas
        .css({animationProgress: 0})
        .animate({animationProgress: 1}, $.extend({}, this.animation, {
          step: function(animationProgress) {
            var stepValue = self.animationStartValue * (1 - animationProgress) + v * animationProgress;
            self.drawFrame(stepValue);
            el.trigger('circle-animation-progress', [animationProgress, stepValue]);
          }
        }))
        .promise()
        .always(function() {
          // trigger on both successful & failure animation end
          el.trigger('circle-animation-end');
        });
    },

    /**
     * Get the circle thickness.
     * @see CircleProgress#thickness
     * @protected
     * @returns {number}
     */
    getThickness: function() {
      return $.isNumeric(this.thickness) ? this.thickness : this.size / 14;
    },

    /**
     * Get current value.
     * @protected
     * @return {number}
     */
    getValue: function() {
      return this.value;
    },

    /**
     * Set current value (with smooth animation transition).
     * @protected
     * @param {number} newValue
     */
    setValue: function(newValue) {
      if (this.animation)
        this.animationStartValue = this.lastFrameValue;
      this.value = newValue;
      this.draw();
    },
    setDuration: function(newValue) {
      if (this.animation)
        this.animationStartValue = this.lastFrameValue;
      this.animation.duration = newValue;
      this.draw();
    }
  };

  //----------------------------------- Initiating jQuery plugin -----------------------------------
  $.circleProgress = {
    // Default options (you may override them)
    defaults: CircleProgress.prototype
  };

  // ease-in-out-cubic
  $.easing.circleProgressEasing = function(x) {
    if (x < 0.5) {
      x = 2 * x;
      return 0.5 * x * x * x;
    } else {
      x = 2 - 2 * x;
      return 1 - 0.5 * x * x * x;
    }
  };

  /**
   * Creates an instance of {@link CircleProgress}.
   * Produces [init event]{@link CircleProgress#init} and [animation events]{@link CircleProgress#drawAnimated}.
   *
   * @param {object} [configOrCommand] - Config object or command name.
   *
   * Config example (you can specify any {@link CircleProgress} property):
   *
   * ```js
   * { value: 0.75, size: 50, animation: false }
   * ```
   *
   * Commands:
   *
   * ```js
   * el.circleProgress('widget'); // get the <canvas>
   * el.circleProgress('value'); // get the value
   * el.circleProgress('value', newValue); // update the value
   * el.circleProgress('redraw'); // redraw the circle
   * el.circleProgress(); // the same as 'redraw'
   * ```
   *
   * @param {string} [commandArgument] - Some commands (like `'value'`) may require an argument.
   * @see CircleProgress
   * @alias "$(...).circleProgress"
   */
  $.fn.circleProgress = function(configOrCommand, commandArgument) {
    var dataName = 'circle-progress',
      firstInstance = this.data(dataName);

    if (configOrCommand == 'widget') {
      if (!firstInstance)
        throw Error('Calling "widget" method on not initialized instance is forbidden');
      return firstInstance.canvas;
    }

    if (configOrCommand == 'value') {
      if (!firstInstance)
        throw Error('Calling "value" method on not initialized instance is forbidden');
      if (typeof commandArgument == 'undefined') {
        return firstInstance.getValue();
      } else {
        var newValue = arguments[1];
        return this.each(function() {
          $(this).data(dataName).setValue(newValue);
        });
      }
    }
    if (configOrCommand == 'duration') {
      if (!firstInstance)
        throw Error('Calling "value" method on not initialized instance is forbidden');
      if (typeof commandArgument == 'undefined') {
        return firstInstance.getValue();
      } else {
        var newValue = arguments[1];
        return this.each(function() {
          $(this).data(dataName).setDuration(newValue);
        });
      }
    }

    return this.each(function() {
      var el = $(this),
        instance = el.data(dataName),
        config = $.isPlainObject(configOrCommand) ? configOrCommand : {};

      if (instance) {
        instance.init(config);
      } else {
        var initialConfig = $.extend({}, el.data());
        if (typeof initialConfig.fill == 'string')
          initialConfig.fill = JSON.parse(initialConfig.fill);
        if (typeof initialConfig.animation == 'string')
          initialConfig.animation = JSON.parse(initialConfig.animation);
        config = $.extend(initialConfig, config);
        config.el = el;
        instance = new CircleProgress(config);
        el.data(dataName, instance);
      }
    });
  };
});