Magento 2: Pass variable from phtml to js

In your .phtml please add following code.

<script type="text/x-magento-init">
{
    "*": {
        "Magepow_Ajaxcart/js/view/minicartaddons": {
            "maxpriceShipping": <?= /* @escapeNotVerified */ $maxpriceShipping ?>
        }
    }
}

And in your JS file please add below code to get maxpriceShipping

define([
       'ko',
       'uiComponent',
       'Magento_Customer/js/customer-data',
   ], function (ko, Component, customerData) {
       'use strict';
       var subtotalAmount;    
       var percentage;
       return Component.extend({
           displaySubtotal: ko.observable(true),
           maxprice:maxPrice.toFixed(2),
           /**
            * @override
            */
           initialize: function () {
               this._super();
               this.cart = customerData.get('cart');
               /* Add this code to get maxpriceShipping value*/
               /* You can use this variable to call this function in your JS*/
               this.maxPrice = ko.observable(this.maxpriceShipping);
               /* Code End*/
           },
           getTotalCartItems: function () {
               return customerData.get('cart')().summary_count;
           },
           getpercentage: function () {
               subtotalAmount = customerData.get('cart')().subtotalAmount;
               if (subtotalAmount > this.maxPrice) {
                   subtotalAmount = this.maxPrice;
               }
               percentage = ((subtotalAmount * 100) / this.maxPrice);
               return percentage;
           }
       });
   });

Please check and let me know in case of any issue.