<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<!-- 1. 原始事件绑定方式，通过标签绑定，不推荐-->
<input onblur="validate2()" onfocus="validate1()" type="text" name="username" id="username">
<span id="error"></span>
<script>
function validate1() {
var _v = document.getElementById("username");
_v.style.border = "solid 2px red";
}
function validate2() {
var _v = document.getElementById("username");
_v.style.border = "none";
if (_v.value.length <= 6) {
document.getElementById("error").textContent = "账号必须大于6位"
} else {
document.getElementById("error").textContent = "";
}
}
</script>
</body>
</html>
1.png
2.png
3.png
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