JS【判断输入表单是否为空、两次输入密码是否相同】

HTML:

	
	
	



	
Your name: 
	
Choose a password: 
	
Verify password: 
	
 

CSS

body {
	color: #000;
	background-color: #FFF;
}

input.invalid {
	background-color: #FF9;
	border: 2px red inset;
}

label.invalid {
	color: #F00;
	font-weight: bold;
}

JS

window.onload = initForms;

function initForms() {
	for (var i=0; i< document.forms.length; i++) {
		document.forms[i].onsubmit = validForm;
	}
}

function validForm() {
	var allGood = true;
	var allTags = document.getElementsByTagName("*");

	for (var i=0; i -1) {
			thisTag.focus();
			if (thisTag.nodeName == "INPUT") {
				thisTag.select();
			}
			return false;
		}
		return true;
		
		function validBasedOnClass(thisClass) {
			var classBack = "";
		
			switch(thisClass) {
				case "":
				case "invalid":
					break;
				case "reqd":
					if (allGood && thisTag.value == "") {
						classBack = "invalid ";
					}
					classBack += thisClass;
					break;
				default:
					if (allGood && !crossCheck(thisTag,thisClass)) {
						classBack = "invalid ";
					}
					classBack += thisClass;
			}
			return classBack;
		}
				
		function crossCheck(inTag,otherFieldID) {
			if (!document.getElementById(otherFieldID)) {
				return false;
			}
			return (inTag.value == document.getElementById(otherFieldID).value);
		}
	}
}