var str = "hello world! this is john,and that is leeo;";
var result = str.split(" ");
for(var i = 0; i < str.length; i++){
document.write(result[i]+"<br>");
}
//输出中有n多的undefined?
var result = str.split(" ");
for(var i = 0; i < str.length; i++){
document.write(result[i]+"<br>");
}
//输出中有n多的undefined?
var result = str.split(" ");
for(var i = 0; i < result.length; i++){
document.write(result[i] + "<br>");
}