javascript - 如何使此代码更有用(防止文本区域中出现特殊字符)

Question

我正在使用这段代码并且工作正常，但这段代码的问题是，它没有优化，举个例子，如果我想添加更多的字符，那么我最终会得到 ifs....

if (keychar == "#" || keychar == "!" || keychar == "$" ..........)

有没有办法优化这段代码？意味着更少的ifs(如果我需要添加更多特殊字符来防止)

 <script language="javascript" type="text/javascript">
        function check(e) {
            var keynum
            var keychar
            var numcheck
            // For Internet Explorer
            if (window.event) {
                keynum = e.keyCode
            }
            // For Netscape/Firefox/Opera
            else if (e.which) {
                keynum = e.which
            }
            keychar = String.fromCharCode(keynum)
            //List of special characters you want to restrict
            if (keychar == "'" || keychar == "a") {

                return false;
            }
            else {
                return true;
            }
        }
</script>

Answer 1

switch(keychar) {
    case "#":
    case "!":
    case "$":
       ...
    default:
       ...
}

或

if( keychar.match(/[#!$]/))