3 Jquery ways to limit the text box to only numbers and letters_jquery

//------------------------------------------------ -----------------------
//

// Limit input to numbers only
//

//------------------------------------------------ -----------------------
$.fn.onlyNum = function () {
$(this).keypress(function (event) {
        var eventObj = event || e;
          var keyCode = eventObj.keyCode || eventObj.which;
If ((keyCode >= 48 && keyCode <= 57))
             return true;
        else
              return false;
}).focus(function () {
//Disable input method
This.style.imeMode = 'disabled';
}).bind("paste", function () {
//Get the contents of the clipboard
      var clipboard = window.clipboardData.getData("Text");
If (/^d $/.test(clipboard))
             return true;
        else
              return false;
});
};

//------------------------------------------------ -----------------------
//

//Limit the input to only letters
//

//------------------------------------------------ -----------------------
$.fn.onlyAlpha = function () {
$(this).keypress(function (event) {
        var eventObj = event || e;
          var keyCode = eventObj.keyCode || eventObj.which;
If ((keyCode >= 65 && keyCode <= 90) || (keyCode >= 97 && keyCode <= 122))
             return true;
        else
              return false;
}).focus(function () {
This.style.imeMode = 'disabled';
}).bind("paste", function () {
      var clipboard = window.clipboardData.getData("Text");
If (/^[a-zA-Z] $/.test(clipboard))
             return true;
        else
              return false;
});
};

// ----------------------------------------------------------------------
//

// 限制只能输入数字和字母
//

// ----------------------------------------------------------------------
$.fn.onlyNumAlpha = function () {
    $(this).keypress(function (event) {
        var eventObj = event || e;
        var keyCode = eventObj.keyCode || eventObj.which;
        if ((keyCode >= 48 && keyCode <= 57) || (keyCode >= 65 && keyCode <= 90) || (keyCode >= 97 && keyCode <= 122))
            return true;
        else
            return false;
    }).focus(function () {
        this.style.imeMode = 'disabled';
    }).bind("paste", function () {
        var clipboard = window.clipboardData.getData("Text");
        if (/^(d|[a-zA-Z]) $/.test(clipboard))
            return true;
        else
            return false;
    });
};

$(function () {
    // 限制使用了onlyNum类样式的控件只能输入数字
    $(".onlyNum").onlyNum();
    //限制使用了onlyAlpha类样式的控件只能输入字母
    $(".onlyAlpha").onlyAlpha();
    // 限制使用了onlyNumAlpha类样式的控件只能输入数字和字母
    $(".onlyNumAlpha").onlyNumAlpha();