<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>JS判断输入框的值是否为空</title>
</head>
<body>
<input type="text" id="txt"/>
<input type="button" value="检测" id="btn">
<script>
var oTxt = document.getElementById('txt');
var oBtn = document.getElementById('btn');
function isnull(val) {
var str = val.replace(/(^\s*)|(\s*$)/g, '');//去除空格;
if (str == '' || str == undefined || str == null) {
//return true;
console.log('空')
} else {
//return false;
console.log('非空');
}
}
oBtn.onclick = function () {
isnull( oTxt.value );
}
</script>
</body>
</html>
