js 正则判断字符串下划线的长度

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>js判断字符串是否有下划线</title>    
    <script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
</head>
<body>
    <script>
        var str="SH_20181030_1_25000";
        var a=str.length;        
        var str1 = str.replace(/\_+/g,"")
        var b=str1.length;
        var c=a-b;
        if(c!==3){
            alert('名字下划线有问题');
        }else{
            alert("ok");
        }
        
    </script>
</body>
</html>

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转载自www.cnblogs.com/quitpoison/p/9895250.html