清除间隔（）不工作

Question

会话长度是定时器的开始时间，默认为25。isEven用于启动/停止定时器，如果isEven为false，定时器应该启动，如果是奇数则应该命中clearInterval，出于某种原因没有停止执行 tick() 函数（它倒计时）。

var count = 0;

function countdown(sessionLength) {
  var minutes = sessionLength - 1;
  var seconds = 60;
  var isEven = false;
  count++;

  if (count % 2 == 0) {
    isEven = true;
  } else {
    isEven = false;
  }

  var myVar = setInterval(tick, 1000);

  if (isEven == false) {
    function tick() {
      if (seconds > 0) {
        seconds--;
      } else {
        minutes--;
        seconds = 59;
      }

      if (minutes > 0) {
        document.getElementById("time").innerHTML =
          minutes.toString() + ":" + (seconds < 10 ? "0" : "") + seconds.toString();
      } else {
        document.getElementById("time").innerHTML =
          "0:" + (seconds < 10 ? "0" : "") + seconds.toString();
      }
    }
  } else {
    console.log("reached");
    clearInterval(myVar);
  }
};

Answer 1

将tick() 函数声明移到if 块之外

Answer 2

setInterval 变量是本地变量。所以每次调用countdown时它的值都会被覆盖

。解决方案是在函数 countdown 之外初始化 myVar 或使其成为像这样的全局变量：
window.myVar =setInterval (tick,1000);

您还必须将此指令放在第一个 if 块中，以免每次都被覆盖

var count = 0;  
function  countdown(sessionLength)  { 
var minutes = sessionLength - 1; 
var seconds = 60; 
var isEven = false; 
count++; 
if (count % 2 == 0) { 
    isEven = true; 
} else { 
    isEven = false;
} 
if (isEven == false) { 
    window.myVar = setInterval(tick, 1000);
   function tick() { 
      if (seconds > 0) {  
          seconds--;  
      } else {  
          minutes--; seconds = 59;  
      } 
      if (minutes > 0)  {  
         document.getElementById("time").innerHTML = minutes.toString() + ":" + (seconds < 10 ? "0" : "") + seconds.toString();  
     } else { 
          document.getElementById("time").innerHTML = "0:" + (seconds < 10 ? "0" : "") + seconds.toString(); 
     } 
   } 
} else { 
     console.log("reached");  
     if (window.myVar){  
          clearInterval(window.myVar); 
          window.myVar = null;
      }
} 
};