当你想要使用javascript的时候你把钥匙扣下来，但是只想玩一次，你如何规避重复的keydown消息？

问题描述

我有一段代码看起来像下面，它的工作正常。它的作用是当鼠标点击一个名为synth的div时启动振荡器声音。然后当鼠标按钮释放时，它会停止播放振荡器。

  synth.onmousedown = function（）{
振荡器= context.createOscillator（），//创建振荡器
 oscillator.type = synthWaveform.value; 
 oscillator.frequency.value = pitchInput.value; 
 osc.connect（context.destination）; //将其连接到输出
 oscillator.noteOn（0）; 
 
 
}; 
 
 
 
 synth.onmouseup = function（）{
 oscillator.disconnect（）; 
 
}; 
  

然后，我添加了以下代码，以便用户按下键盘字符时触发振荡器。问题是，当按住键时，它会弹出播放，然后当键盘字符被释放时不会停止。我想知道是否有任何图书馆或代码可以用来规避这个。目标是让最终的结果像一个mousedown / up效果，但键盘运动触发声音。谢谢。

  $（'body'）。keydown（function（）{
 oscillator = context.createOscillator（），//创建振荡器
 oscillator.type = synthWaveform.value; 
 osc.frequency。 value = pitchInput.value; 
振荡器连接（context.destination）; //将其连接到输出
 oscillator.noteOn（0）; 
}）; 
 
 $（'body'）。keyup（function（）{
 oscillator.disconnect（）; 
 
}）; 
  

解决方案

你可以使用underscore.js去抖动，如果你需要的东西优于下列选项。

  var keydown = false; 
 
 $（'body'）。keydown（function（）{
 if（！keydown）{
 oscillator = context.createOscillator（），//创建振荡器
振荡器类型= synthWaveform.value; 
振荡器frequency.value = pitchInput.value; 
振荡器连接（context.destination）; //将其连接到输出
 osc.noteOn （0）; 
 keydown = true; 
} 
}）; 
 
 $（'body'）。keyup（function（）{
 oscillator.disconnect（）; 
 keydown = false; 
}）; 
  

I have a piece of code that looks something like below and it works fine. What it does is it launches an oscillator sound when the mouse clicks on a div named synth.It then stops playing the oscillator when the mouse button is released.

 synth.onmousedown= function () {
    oscillator = context.createOscillator(),  // Creates the oscillator 
    oscillator.type = synthWaveform.value;  
    oscillator.frequency.value = pitchInput.value;                   
    oscillator.connect(context.destination);  // Connects it to output
    oscillator.noteOn(0); 


    };



    synth.onmouseup = function ()    {  
    oscillator.disconnect(); 

    };

I then added the code below so that when a user presses a keyboard charachter it triggers the oscillator. The problem is that when the key is held down it repeadedly plays and then won't stop when the keyboard character is released. I want to know if there are any libraries or code that can be used to circumvent this. The goal is to have the end result be like a mousedown/up effect but with keyboard movements triggering the sound.Thank you.

$('body').keydown(function() {
oscillator = context.createOscillator(),  // Creates the oscillator 
oscillator.type = synthWaveform.value;  
oscillator.frequency.value = pitchInput.value;                   
oscillator.connect(context.destination);  // Connects it to output
oscillator.noteOn(0); 
});

$('body').keyup(function() {
oscillator.disconnect();

});

解决方案

you could use underscore.js debounce if you need something fancier than the below option.

var keydown = false;

$('body').keydown(function() {
    if(!keydown){
        oscillator = context.createOscillator(),  // Creates the oscillator 
        oscillator.type = synthWaveform.value;  
        oscillator.frequency.value = pitchInput.value;                   
        oscillator.connect(context.destination);  // Connects it to output
        oscillator.noteOn(0);
        keydown = true;
    }
});

$('body').keyup(function() {
    oscillator.disconnect();
    keydown = false;
});

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