如何在javascript中替换字符串变量的值？

Question

I need a way to switch between two modes when a button is pressed.

The analogy of my problem:

A button is pushed "on and off" and an alert says "On" or "Off"

How do I get string to alternate between the values: "On" and "Off" by updating the value of string every time I push the button which checks current value and replaces?

interface

<button onclick="changeState();">Push me</button>

script

<script> 

var string = "up"; 

function changeState(){

  if(string=="up"){
  // switching to off
    var string = "down"; // I'm just redeclaring or declaring a new variable right? scope? 
    alert(Off);
    }else{
    // switching to on assuming current state is off
      var string = "up";
      // new state
      alert('on');
    }

  }

}
</script>

Answer 1

Here you are. I remove 'var' let it global, also remove a } spare:

 var string = "up"; function changeState() { if (string == "up") { // switching to off string = "down"; // I'm just redeclaring or declaring a new variable right? scope? alert("off"); } else { // switching to on assuming current state is off string = "up"; // new state alert('on'); } }

 <button onclick="changeState()">Push me</button>

Hope this help.

Answer 2

 var string = "up"; function changeState() { string = string =="up" ? "down" : "up"; }