Java regular expression 3: the application of regular expressions in JavaScript; (small example of string verification)

One: Application examples of regular expressions in JavaScript:

For example, when the front-end interface submits a form, the content of the input box in the form needs to be verified. If the input rules are met, the verification is successful, and the form is submitted; if the input rules are not met, the verification is unsuccessful, and a related error message is displayed.

Regular expressions are often used to verify this requirement ;

index.html：

(1) When defining the regular expression object in JavaScript: var regex1 = /^[\u4e00-\u9fa5]{2,8}$/; That is, it is defined in the middle of the two slashes, and a variable is used to receive it ;

(2) The test() method of the regular expression object in JavaScript is used to verify whether the string complies with the regular expression verification rules;

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>

	<form action="#" method="post" id="frmInfo">
		<div id="err" style="color:red">
		</div>
		<div>  
			姓名:<input id="name" name="name" />
		</div>
		<div>
			身份证:<input id="idNo" name="idNo" />
		</div>
		<div>
			<input type="submit"/>
		</div>
	</form>
	<script type="text/javascript">
		document.getElementById("frmInfo").onsubmit = function(){
			//在JavaScript中定义的正则表达式对象，只需要在两个斜杠中间书写正则表达式后，就能在JavaScript中获得一个正则表达式对象，
			// 然后用一个变量去接受就可以了；
			var regex1 = /^[\u4e00-\u9fa5]{2,8}$/; // 校验姓名的正则表达时
			var regex2 = /^[1234568]\d{16}[0-9xX]$/;// /^[1234568]\d{16}[\dxX]$/这样写，经过实测也是可以的哦
			var name = document.getElementById("name").value;
			var idNo = document.getElementById("idNo").value;
			if(regex1.test(name) == false){// JavaScript的正则表达式对象提供了test()方法，返回值为true(匹配)或false(不匹配)；
				document.getElementById("err").innerHTML = "无效姓名";
				return false;
			}else if(regex2.test(idNo) == false){
				document.getElementById("err").innerHTML = "无效idNo";
				return false;
			}
			else{
				return true;
			}
			  
		}
	
	</script>
</body>
</html>

Above, the name and id are verified, like this step by step one by one. When doing projects before, this structure of if else judgment was adopted. This structure can be a good location for positioning. An error in an input box is convenient for pop-up prompts;

effect:

In fact, fortunately, when checking the input box in JavaScript, it should be plug and play, and the attitude of using it as you want should be fine~~~

Then, the application of regular expressions in JavaScript must have many other aspects, follow-up additions...

Then, the form input item verification work is generally used to be handed over to the front-end to solve it?

Java regular expression 3: the application of regular expressions in JavaScript; (small example of string verification)

One: Application examples of regular expressions in JavaScript:

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