fix(@vant/touch-emulator): add SSR support (#8767)

packages/vant-touch-emulator/index.js

@@ -4,12 +4,16 @@
  * Source：https://github.com/hammerjs/touchemulator
  */
 
-var eventTarget;
-var supportTouch = 'ontouchstart' in window;
+(function () {
+  if (typeof window === 'undefined') {
+    return;
+  }
+  var eventTarget;
+  var supportTouch = 'ontouchstart' in window;
 
-// polyfills
-if (!document.createTouch) {
-  document.createTouch = function(
+  // polyfills
+  if (!document.createTouch) {
+    document.createTouch = function (
       view,
       target,
       identifier,
@@ -34,10 +38,10 @@ if (!document.createTouch) {
         0
       );
     };
-}
+  }
 
-if (!document.createTouchList) {
-  document.createTouchList = function() {
+  if (!document.createTouchList) {
+    document.createTouchList = function () {
       var touchList = TouchList();
       for (var i = 0; i < arguments.length; i++) {
         touchList[i] = arguments[i];
@@ -45,9 +49,9 @@ if (!document.createTouchList) {
       touchList.length = arguments.length;
       return touchList;
     };
-}
+  }
 
-/**
+  /**
    * create an touch point
    * @constructor
    * @param target
@@ -58,7 +62,7 @@ if (!document.createTouchList) {
    * @returns {Object} touchPoint
    */
 
-var Touch = function Touch(target, identifier, pos, deltaX, deltaY) {
+  var Touch = function Touch(target, identifier, pos, deltaX, deltaY) {
     deltaX = deltaX || 0;
     deltaY = deltaY || 0;
 
@@ -70,37 +74,37 @@ var Touch = function Touch(target, identifier, pos, deltaX, deltaY) {
     this.screenY = pos.screenY + deltaY;
     this.pageX = pos.pageX + deltaX;
     this.pageY = pos.pageY + deltaY;
-};
+  };
 
-/**
+  /**
    * create empty touchlist with the methods
    * @constructor
    * @returns touchList
    */
-function TouchList() {
+  function TouchList() {
     var touchList = [];
 
-  touchList['item'] = function(index) {
+    touchList['item'] = function (index) {
       return this[index] || null;
     };
 
     // specified by Mozilla
-  touchList['identifiedTouch'] = function(id) {
+    touchList['identifiedTouch'] = function (id) {
       return this[id + 1] || null;
     };
 
     return touchList;
-}
+  }
 
-/**
+  /**
    * only trigger touches when the left mousebutton has been pressed
    * @param touchType
    * @returns {Function}
    */
 
-var initiated = false;
-function onMouse(touchType) {
-  return function(ev) {
+  var initiated = false;
+  function onMouse(touchType) {
+    return function (ev) {
       // prevent mouse events
 
       if (ev.type === 'mousedown') {
@@ -133,14 +137,14 @@ function onMouse(touchType) {
         eventTarget = null;
       }
     };
-}
+  }
 
-/**
+  /**
    * trigger a touch event
    * @param eventName
    * @param mouseEv
    */
-function triggerTouch(eventName, mouseEv) {
+  function triggerTouch(eventName, mouseEv) {
     var touchEvent = document.createEvent('Event');
     touchEvent.initEvent(eventName, true, true);
 
@@ -154,44 +158,45 @@ function triggerTouch(eventName, mouseEv) {
     touchEvent.changedTouches = createTouchList(mouseEv);
 
     eventTarget.dispatchEvent(touchEvent);
-}
+  }
 
-/**
+  /**
    * create a touchList based on the mouse event
    * @param mouseEv
    * @returns {TouchList}
    */
-function createTouchList(mouseEv) {
+  function createTouchList(mouseEv) {
     var touchList = TouchList();
     touchList.push(new Touch(eventTarget, 1, mouseEv, 0, 0));
     return touchList;
-}
+  }
 
-/**
+  /**
    * receive all active touches
    * @param mouseEv
    * @returns {TouchList}
    */
-function getActiveTouches(mouseEv) {
+  function getActiveTouches(mouseEv) {
     // empty list
     if (mouseEv.type === 'mouseup') {
       return TouchList();
     }
     return createTouchList(mouseEv);
-}
+  }
 
-/**
+  /**
    * TouchEmulator initializer
    */
-function TouchEmulator() {
+  function TouchEmulator() {
     window.addEventListener('mousedown', onMouse('touchstart'), true);
     window.addEventListener('mousemove', onMouse('touchmove'), true);
     window.addEventListener('mouseup', onMouse('touchend'), true);
-}
+  }
 
-// start distance when entering the multitouch mode
-TouchEmulator['multiTouchOffset'] = 75;
+  // start distance when entering the multitouch mode
+  TouchEmulator['multiTouchOffset'] = 75;
 
-if (!supportTouch) {
+  if (!supportTouch) {
     new TouchEmulator();
-}
+  }
+})();