微型的javascript REPL

REPL(Read Eval Print Loop)是一种非常有用的工具，能让我们即时运行代码得到结果。虽然相比于firebug的控制台来说，这简直不值一提，但在个人博客中提供演示时它还是比较有用。

下面是它的所有代码，包括html。

<textarea style="width:100%" onkeyup="

  this.rows=(function(t){

    for (var i=0,h=1;i<t.length;i++) if (t.charAt(i) == '\n') h++;

    return h;

  })(this.value);

">

//---------------------这是示例-----

var now = new Date;

var pad = function(num,  digits, radix, filling){

     num = num.toString(radix || 10);

     filling = filling || "0";

     while(num.length < digits){

         num= filling + num;

     }

     return num;

}

now = now.getFullYear()+"-"+pad(now.getMonth()+1,2)+"-"+pad(now.getDate(),2);

p(now);

//-----------------------------------

</textarea><input type="submit" value="Eval" onclick="

  try{

    var o = this.nextSibling.nextSibling;

    var p = function(s){

      var e = document.createElement('p');

      e.appendChild(document.createTextNode(s));

      e.style.margin=0;

      o.appendChild(e);

    };

    (new Function('p',this.previousSibling.value))(p);

  }catch(e){

    alert(e)

  }

"><input type="submit" value="Clear" onclick="

  this.nextSibling.innerHTML=''

"><div style="border:inset 1px;padding:0.5em"></div>

//---------------------这是示例----- var now = new Date; var pad = function(num, digits, radix, filling){ num = num.toString(radix || 10); filling = filling || "0"; while(num.length < digits){ num= filling + num; } return num; } now = now.getFullYear()+"-"+pad(now.getMonth()+1,2)+"-"+pad(now.getDate(),2); p(now); //-----------------------------------