只限制输入数字

具有在输入非数字字符不回显的效果，即对非数字字符的输入不作反应。
[code]
function numbersonly(field,event){
var key,keychar;
if(window.event){
key = window.event.keyCode;
}
else if (event){
key = event.which;
}
else{
return true
}
keychar = String.fromCharCode(key);
if((key == null)||(key == 0)||(key == 8)||(key == 9)||(key == 13)||(key == 27)){
return true;
}
else if((“0123456789.”).indexOf(keychar)>-1){
window.status = “”;
return true;
}
else {
window.status = “Field excepts numbers only”;
return false;
}
}
[/code]