javascript获取键盘keydown和keyup输入

Question

I want to send server when client does keydown or keyup.

However, sometimes It doesn't work well. It misses some event and "keyboard array" doesn't [] when I leave my hands to keyboard.

I maked "keyboard array" to find duplicate input, and when window is not focused I initialized it. Here's my code.

var keyarr = [];
window.onkeyup = function(e){
    if(keyarr.indexOf(e.keyCode) != -1) {
            //delete keyCode
        keyarr.splice(keyarr.indexOf(e.keyCode),1);
            //websocket.send(keycode);
    }
}
window.onkeydown = function(e){
      //check keyCode available
      if(!e.repeat && keyarr.indexOf(e.keyCode) == -1) {
            //add keyCode
            keyarr.push(e.keyCode);
            //websocket.send(keycode);
      }
}
window.onblur = function(){
      keyarr = [];
      //websocket.send(keycode);
}

Why some keydown and keyup event doesn't delivered well?

Answer 1

To answer your question:

It can be due to WI-FI connections or computer performance. But I'll try to help you optimize your code a bit to make it work better

Let's get couple thing out of the way:

• WTH is your dict variable and what does it represent. Please be more explicit

• The sections:

  dict[e.keyCode] != undefined

  Can be replaced with:

  dict[e.keyCode]

• In this section:

  if(dict[e.keyCode] != undefined && keyarr.indexOf(e.keyCode) != -1) {
  //delete keyCode
  keyarr.splice(keyarr.indexOf(e.keyCode),1);
  }
  

  You're looking up the index of the keycode in the array TWICE. Store keyarr.indexOf(e.keyCode) in a local variable