javascript generates a random number of bits specified

<script type="text/javascript">

		Document .write ( "Please enter the number of bits to generate a random number:" ); 
			// number of digits is the digit for 
			function  runStr (digit for) { 
				IF (digit for == ""  ||  isNaN (digit for)) { 
					Alert ( " Please enter the number " ); 
				} the else { 
					var  sourceStr = " 0,1,2,3,4,5,6,7,8,9, A, B, C, D, E, F., G " ; 
					arrStr = sourceStr.split ( "," ); 
					var  Result = "" ;  // define and initialize the variable 
					var  index = 0 ; 
					for (I = 0 ; I <digit for; I ++) { 
						index = the parseInt ( the Math.random()*arrStr.length);
						result+=arrStr[index];
					}
					alert(result);
				}

			}


		</script>

		<form name="form">
			<input type="text" name="digit"/>
			<input type="button" value="生成" onClick="runStr(form.digit.value)">
		</form>