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js實現商品拋物線加入購物車特效
編輯:關於JavaScript     

本文實例為大家分享了js實現商品拋物線加入購物車動畫代碼,供大家參考,具體內容如下

 

parapola.js

/*!
 * by zhangxinxu(.com) 2012-12-27
 * you can visit http://www.zhangxinxu.com/wordpress/?p=3855 to get more infomation
 * under MIT license
*/
var funParabola = function(element, target, options) {
  /*
   * 網頁模擬現實需要一個比例尺
   * 如果按照1像素就是1米來算,顯然不合適,因為頁面動不動就幾百像素
   * 頁面上,我們放兩個物體,200~800像素之間,我們可以映射為現實世界的2米到8米,也就是100:1
   * 不過,本方法沒有對此有所體現,因此不必在意
  */
  
  var defaults = {
    speed: 166.67, // 每幀移動的像素大小,每幀(對於大部分顯示屏)大約16~17毫秒
    curvature: 0.001, // 實際指焦點到准線的距離,你可以抽象成曲率,這裡模擬扔物體的拋物線,因此是開口向下的
    progress: function() {},
    complete: function() {}
  };
  
  var params = {}; options = options || {};
  
  for (var key in defaults) {
    params[key] = options[key] || defaults[key];
  }
  
  var exports = {
    mark: function() { return this; },
    position: function() { return this; },
    move: function() { return this; },
    init: function() { return this; }
  };
  
  /* 確定移動的方式 
   * IE6-IE8 是margin位移
   * IE9+使用transform
  */
  var moveStyle = "margin", testDiv = document.createElement("div");
  if ("oninput" in testDiv) {
    ["", "ms", "webkit"].forEach(function(prefix) {
      var transform = prefix + (prefix? "T": "t") + "ransform";
      if (transform in testDiv.style) {
        moveStyle = transform;
      }
    });    
  }
  
  // 根據兩點坐標以及曲率確定運動曲線函數(也就是確定a, b的值)
  /* 公式: y = a*x*x + b*x + c;
  */
  var a = params.curvature, b = 0, c = 0;
  
  // 是否執行運動的標志量
  var flagMove = true;
  
  if (element && target && element.nodeType == 1 && target.nodeType == 1) {
    var rectElement = {}, rectTarget = {};
    
    // 移動元素的中心點位置,目標元素的中心點位置
    var centerElement = {}, centerTarget = {};
    
    // 目標元素的坐標位置
    var coordElement = {}, coordTarget = {};
    
    // 標注當前元素的坐標
    exports.mark = function() {
      if (flagMove == false) return this;
      if (typeof coordElement.x == "undefined") this.position();
      element.setAttribute("data-center", [coordElement.x, coordElement.y].join());
      target.setAttribute("data-center", [coordTarget.x, coordTarget.y].join());
      return this;
    }
    
    exports.position = function() {
      if (flagMove == false) return this;
      
      var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft,
        scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
      
      // 初始位置
      if (moveStyle == "margin") {
        element.style.marginLeft = element.style.marginTop = "0px";
      } else {
        element.style[moveStyle] = "translate(0, 0)";
      }
      
      // 四邊緣的坐標
      rectElement = element.getBoundingClientRect();
      rectTarget = target.getBoundingClientRect();
      
      // 移動元素的中心點坐標
      centerElement = {
        x: rectElement.left + (rectElement.right - rectElement.left) / 2 + scrollLeft,
        y: rectElement.top + (rectElement.bottom - rectElement.top) / 2  + scrollTop
      };
      
      // 目標元素的中心點位置
      centerTarget = {
        x: rectTarget.left + (rectTarget.right - rectTarget.left) / 2 + scrollLeft,
        y: rectTarget.top + (rectTarget.bottom - rectTarget.top) / 2 + scrollTop    
      };
      
      // 轉換成相對坐標位置
      coordElement = {
        x: 0,
        y: 0  
      };
      coordTarget = {
        x: -1 * (centerElement.x - centerTarget.x),
        y: -1 * (centerElement.y - centerTarget.y)  
      };
      
      /*
       * 因為經過(0, 0), 因此c = 0
       * 於是:
       * y = a * x*x + b*x;
       * y1 = a * x1*x1 + b*x1;
       * y2 = a * x2*x2 + b*x2;
       * 利用第二個坐標:
       * b = (y2+ a*x2*x2) / x2
      */
      // 於是
      b = (coordTarget.y - a * coordTarget.x * coordTarget.x) / coordTarget.x;  
      
      return this;
    };    
    
    // 按照這個曲線運動
    exports.move = function() {
      // 如果曲線運動還沒有結束,不再執行新的運動
      if (flagMove == false) return this;
      
      var startx = 0, rate = coordTarget.x > 0? 1: -1;

      var step = function() {
        // 切線 y'=2ax+b
        var tangent = 2 * a * startx + b; // = y / x
        // y*y + x*x = speed
        // (tangent * x)^2 + x*x = speed
        // x = Math.sqr(speed / (tangent * tangent + 1));
        startx = startx + rate * Math.sqrt(params.speed / (tangent * tangent + 1));
        
        // 防止過界
        if ((rate == 1 && startx > coordTarget.x) || (rate == -1 && startx < coordTarget.x)) {
          startx = coordTarget.x;
        }
        var x = startx, y = a * x * x + b * x;
        
        // 標記當前位置,這裡有測試使用的嫌疑,實際使用可以將這一行注釋
        element.setAttribute("data-center", [Math.round(x), Math.round(y)].join());
        
        // x, y目前是坐標,需要轉換成定位的像素值
        if (moveStyle == "margin") {
          element.style.marginLeft = x + "px";
          element.style.marginTop = y + "px";
        } else {
          element.style[moveStyle] = "translate("+ [x + "px", y + "px"].join() +")";
        }
        
        if (startx !== coordTarget.x) {
          params.progress(x, y);
          window.requestAnimationFrame(step);  
        } else {
          // 運動結束,回調執行
          params.complete();
          flagMove = true;  
        }
      };
      window.requestAnimationFrame(step);
      flagMove = false;
      
      return this;
    };
    
    // 初始化方法
    exports.init = function() {
      this.position().mark().move();
    };
  }
  
  return exports;
};

/*! requestAnimationFrame.js
 * by zhangxinxu 2013-09-30
*/
(function() {
  var lastTime = 0;
  var vendors = ['webkit', 'moz'];
  for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
    window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
    window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame'] ||  // name has changed in Webkit
                   window[vendors[x] + 'CancelRequestAnimationFrame'];
  }

  if (!window.requestAnimationFrame) {
    window.requestAnimationFrame = function(callback, element) {
      var currTime = new Date().getTime();
      var timeToCall = Math.max(0, 16.7 - (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);
    };
  }
}());

使用:

/* 元素 */
var element = document.getElementById("element"), 
  target = document.getElementById("target");
// 拋物線元素的的位置標記
var parabola = funParabola(element, target).mark();
// 拋物線運動的觸發
document.body.onclick = function() {
  element.style.marginLeft = "0px";
  element.style.marginTop = "0px";
  parabola.init();
};

加入購物車實戰:

/* 本demo演示腳本基於ieBetter.js, 項目地址:https://github.com/zhangxinxu/ieBetter.js */

// 元素以及其他一些變量
var eleFlyElement = document.querySelector("#flyItem"), eleShopCart = document.querySelector("#shopCart");
var numberItem = 0;
// 拋物線運動
var myParabola = funParabola(eleFlyElement, eleShopCart, {
  speed: 400,
  curvature: 0.002,  
  complete: function() {
    eleFlyElement.style.visibility = "hidden";
    eleShopCart.querySelector("span").innerHTML = ++numberItem;
  }
});
// 綁定點擊事件
if (eleFlyElement && eleShopCart) {
  [].slice.call(document.getElementsByClassName("btnCart")).forEach(function(button) {
    button.addEventListener("click", function() {
      // 滾動大小
      var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft || 0,
        scrollTop = document.documentElement.scrollTop || document.body.scrollTop || 0;

      eleFlyElement.style.left = event.clientX + scrollLeft + "px";
      eleFlyElement.style.top = event.clientY + scrollTop + "px";
      eleFlyElement.style.visibility = "visible";
      
      // 需要重定位
      myParabola.position().move(); 
    });
  });
}

以上就是本文的全部內容,希望對大家的學習有所幫助。

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