Firebase hitcounter:点击显示，但不会增加

Question

我正在尝试制作一个显示在我的页面控制台中的点击计数器。相关代码如下：

    var database = firebase.database();



   database.ref().on("value", function(snapshot) {

      console.log("Logging snapshot.val " + snapshot.val());

      console.log("Logging hits " + snapshot.val().hits);

      var hitCounter = snapshot.val().hits;

      console.log("hitCounter is " + hitCounter)
    }, function(errorObject) {

      console.log("The read failed: " + errorObject.code);
    });

//so I can get it to display the value in the database, but not to increase.  WTF
  function showStuff() {
    $("#content").fadeIn("slow");

      hitCounter++;
      console.log("hitCounter in showstuff() function is = " + hitCounter);
      //this console log above doesn't even fire.  WTF!?
      //Ask on stack overflow some other time

      database.ref().set({
        hits: hitCounter
      });


}

正如注释所示，我可以让数据库中的数字显示，但不能增加。甚至showStuff()中的console.log也不会触发(但是淡入会触发)。到底怎么回事？

Answer 1

您正在使用的事件回调将在每次更改数据时向其传递快照。如果需要使用showStuff函数显示该值，则必须在回调函数中调用该函数

 database.ref().on("value", function(snapshot) {
  console.log("Logging snapshot.val " + snapshot.val());
  console.log("Logging hits " + snapshot.val().hits);

  var hitCounter = snapshot.val().hits;
  console.log("hitCounter is " + hitCounter);


  showStuff();

}, function(errorObject) {

  console.log("The read failed: " + errorObject.code);
});