Using JavaScript to get a value using the SharePoint FieldInternalName

From the SharePoint JavaScripts blog:

<script type="text/javascript">  
/*************************************************************  
Type:  
Singelline tekst and multiline tekst (Plain text), Number, Currency  = text  
Multichoice checkbox = checkbox (returns commaseparated values)  
Date (returns date only, but works with both DateOnly and DateAndTime) = date  
RadioButton = radio  
Dropdown = dropdown  
Yes/No = bool  
Hyperlink or picture (returns commaseparated: description,url) = url  
Lookup - single (below and over 20 items), MultiLookup (returns array) = lookup  
Lookup Multiple - you can use plain 'lookup', but if you want only "multi" = lookupMulti  
Person - DisplayName = personDisplay  
Person - LoginName = personLogin  
Use: var value = returnValue('checkbox','FieldInternalNameOfYourField');  
*************************************************************/ 
function returnValue(type, fieldInternalName) {  
var arr = document.getElementsByTagName('!');//get all comments  
for (var i=0;i < arr.length; i++ ) {  
        // Date  
        if (type=='date' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
            var fieldTitle = arr[i].innerHTML.substring(arr[i].innerHTML.indexOf('FieldName=')+11,arr[i].innerHTML.indexOf('\n')-2);  
            var tags = document.getElementsByTagName('input');  
            for (var i=0; i < tags.length; i++) {  
                if (tags[i].title == fieldTitle && tags[i].parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.innerHTML.indexOf('FieldName="'+fieldTitle+'"') > -1)  
                {  
                return tags[i].value;  
                }  
            }  
        // RadioButton - Credit to http://blog.markuso.com/ - slightly modified by me to use FieldInternalName  
        }else if(type=='radio' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
        var tags = document.getElementsByTagName("input");  
            for (var i=0; i < tags.length; i++) {  
            var nameString = tags[i].name;  
            // get selected radio button value only  
            if (tags[i].type == "radio") {  
                var tagParentHTML = tags[i].parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.innerHTML;  
                    if (tagParentHTML.indexOf('FieldInternalName="'+fieldInternalName+'"') > -1) {  
                    var radioButtons = document.getElementsByName(nameString);  
                    var radioValue = "";  
                    for (var x=0; x < radioButtons.length; x++) {  
                        if (radioButtons[x].checked) {  
                            radioValue = radioButtons[x].parentElement.title;  
                            break;  
                        }  
                    }  
                    var o = document.createElement("INPUT");  
                    o.type = "hidden";  
                    o.value = radioValue;  
                    return o.value;  
                    }  
            }  
        }  
        return null;  
        // Checkbox  
        }else if(type=='checkbox') {  
            var arr = [];  
            var arrValue = [];  
            var tags = document.getElementsByTagName("input");  
            for (var i=0; i < tags.length; i++) {  
                if (tags[i].type == "checkbox") {  
                var tagParentHTML = tags[i].parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.parentElement.innerHTML;  
                    if (tagParentHTML.indexOf('FieldInternalName="'+fieldInternalName+'"') > -1) {  
                    arr.push(tags[i].id);  
                    }  
                }  
            }  
                for (var x=0; x < arr.length; x++) {  
                var chkBox = document.getElementById(arr[x]);  
                    if (chkBox.checked) {  
                        arrValue.push(chkBox.parentElement.title);  
                    }  
                }  
            return arrValue.toString();  
        // Text or Dropdown  
        }else if((type=='text' || type=='dropdown') && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
            return arr[i].parentNode.childNodes[1].childNodes[0].value;  
        // Hyperlink or Picture  
        }else if(type=='url' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
            // returns commaseparated (description,url) so it can be split later  
            var hyperlink = [];  
            hyperlink.push(arr[i].parentNode.childNodes[1].childNodes[4].value);  
            hyperlink.push(arr[i].parentNode.childNodes[1].childNodes[1].value);  
            return hyperlink;  
        // Bool  
        }else if(type=='bool' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
            return arr[i].parentNode.childNodes[1].childNodes[0].checked;  
        // Lookup  
        }else if(type=='lookup' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
        // Under 20 items  
        var opt = arr[i].parentNode.childNodes[1].childNodes[0].options;  
            if(opt!=null) {  
                for (var x=0;x<opt.length;x++) {  
                    if(opt[x].selected == true) {  
                        return (opt[x].innerHTML);  
                    }  
                }  
            }else if(opt==null){  
                if(arr[i].parentNode.childNodes[1].childNodes[0].childNodes[0]!= null) {  
                    // Over 20 items  
                    return arr[i].parentNode.childNodes[1].childNodes[0].childNodes[0].value;  
                }else{  
                    // MultiLookup - optionally you can call the script with type='lookupMulti'  
                    var arrSelected = [];  
                    var fieldId = arr[i].parentNode.childNodes[1].childNodes[0].id;  
                    var selectResultId = fieldId.substr(0,fieldId.indexOf('MultiLookupPicker')) + 'SelectResult';  
                    var selectResultField = document.getElementById(selectResultId);  
                        for(var x=0;x < selectResultField.length; x++){  
                        arrSelected.push (selectResultField[x].innerHTML);  
                        }  
                    return arrSelected.toString();  
                }  
            }  
        }  
        // Lookup Multi (can also use plain 'lookup' as spacified above  
        else if(type=='lookupMulti' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
        var arrSelected = [];  
        var fieldId = arr[i].parentNode.childNodes[1].childNodes[0].id;  
        var selectResultId = fieldId.substr(0,fieldId.indexOf('MultiLookupPicker')) + 'SelectResult';  
        var selectResultField = document.getElementById(selectResultId);  
            for(var x=0;x < selectResultField.length; x++){  
            arrSelected.push (selectResultField[x].innerHTML);  
            }  
        return arrSelected.toString();  
        // Person  
        }else if(type=='personDisplay' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
        var rawString = arr[i].parentNode.childNodes[1].innerHTML;  
            if(rawString.indexOf('isresolved="True"')>0){  
            // user resolved OK  
                // Use these for DisplayName  
                var displayName = rawString.indexOf('displaytext="');  
                var start = displayName + 13;  
                var stopp = displayName + rawString.substring(rawString.indexOf('displaytext="')).indexOf('key="')-2;  
                var user = rawString.substring(start, stopp);  
                return user;  
            }else{  
            // user not resolved  
                return "";  
            }  
        }else if(type=='personLogin' && arr[i].innerHTML.match('FieldInternalName="' + fieldInternalName + '"')) {  
        var rawString = arr[i].parentNode.childNodes[1].innerHTML;  
            if(rawString.indexOf('isresolved="True"')>0){  
                // Use these for Loginname  
                var loginName = rawString.indexOf('isresolved="True"');  
                var start = loginName + rawString.substring(rawString.indexOf('isresolved="True"')).indexOf('key="')+5;  
                var stopp = loginName + rawString.substring(rawString.indexOf('isresolved="True"')).indexOf('">');  
                var user = rawString.substring(start, stopp);  
                return user;  
            }else{  
            // user not resolved  
                return "";  
            }  
        }  

    }  
}  
</script>