Javascript String.fromCharCode返回错误的值

Question

我有这个Knockout自定义绑定来验证文本框只包含英文字母.但是,似乎Javascript的String.fromCharCode返回错误值.

例如,希伯来字母"ש"以英文字母"A "返回,而右边数字键盘中的数字"1"返回为"a"...

这是我的Knockout绑定:

var arrValidKeys = [8, 16, 17, 20, 35, 36, 37, 39, 46];
    ko.bindingHandlers.validateText = {
        init: function (element, valueAccessor) {
            $(element).on("keydown", function (event) {

                //Regex pattern: allow only (A to Z uppercase, a to z lowercase)
                var englishAlphabet = /[A-Za-z]/g;

                // Retrieving the key from the char code passed in event.which
                var key = String.fromCharCode(event.which);

                // keyCodes list: http://stackoverflow.com/a/3781360/114029
                // check that the key is valid with the above Regex
                valueAccessor()($(this).val());

                return ((jQuery.inArray(event.keyCode, arrValidKeys) != -1) || englishAlphabet.test(key));
            });

            $(element).on("keyup", function (event) {

                //Regex pattern: allow only (A to Z uppercase, a to z lowercase)
                var englishAlphabet = /[A-Za-z]/g;

                // Retrieving the key from the char code passed in event.which
                var key = String.fromCharCode(event.which);

                // keyCodes list: http://stackoverflow.com/a/3781360/114029
                // check that the key is valid with the above Regex

                valueAccessor()($(this).val());

                return ((jQuery.inArray(event.keyCode, arrValidKeys) != -1) || englishAlphabet.test(key));
            });

            $(element).on("paste", function (e) {
                var englishAlphabet = /[A-Za-z]/g;
                if (englishAlphabet.test($(this).val()))
                    valueAccessor()($(this).val());
                else
                    e.preventDefault();
            });
        }
    };