This section describes the EL functions defined in the built-in TLD called http://www.zkoss.org/dsp/web/core. Declare the taglib once, then call any function with its prefix:

<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>

<window title="${c:l('app.title')}">
 ...
</window>

The table below lists every core function with its signature and purpose; click a name for full details, parameters, and examples.

Function Signature Description
attr String attr(String name, Object value) Generates an HTML/XML attribute name="value"; empty value yields "".
boolean boolean boolean(Object value) Converts an object to a boolean.
browser boolean browser(String type) Tests whether the current request comes from a browser of the given type.
cat String cat(String s1, String s2) Concatenates two strings (null treated as empty).
cat3 String cat3(String s1, String s2, String s3) Concatenates three strings.
cat4 String cat4(String s1, ..., String s4) Concatenates four strings.
cat5 String cat5(String s1, ..., String s5) Concatenates five strings.
char char char(Object value) Converts an object to a character.
class Class class(String className) Returns the class for the given class name.
decimal BigDecimal decimal(Object value) Converts an object to a BigDecimal.
eatQuot String eatQuot(String s) Removes single and double quotes to avoid JavaScript injection.
encodeThemeURL String encodeThemeURL(String url) Encodes a URL with the theme-specific prefix and session info.
encodeURIComponent String encodeURIComponent(String s) HTTP-encodes a URI query parameter (e.g. / → %2F).
encodeURL String encodeURL(String uri) Encodes a URL, resolving * to the current locale/browser.
endsWith boolean endsWith(String value, String suffix) Tests whether the string ends with the suffix.
escapeXML String escapeXML(String s) Escapes special characters to be HTML/XML-safe (< → &lt;, …).
formatDate String formatDate(Date date, String pattern) Formats a Date into a string with the given pattern.
formatNumber String formatNumber(Object number, String pattern) Formats a number into a string with the given pattern.
getCurrentLocale Locale getCurrentLocale() Returns the locale of the current request; never null.
indexOf int indexOf(Object value, Object element) The first index of the element within the value.
int int int(Object value) Converts an object to an int.
isInstance boolean isInstance(Object class, Object value) Tests whether the value is an instance of the given class.
join String join(Object[] value, String separator) Joins an array into a string with the separator.
l String l(String key) Returns the i18n label for the key (current locale).
l2 String l2(String key, Object[] args) Returns the i18n label for the key and formats it with args.
lastIndexOf int lastIndexOf(Object value, Object element) The last index of the element within the value.
length int length(Object value) The length of a string, array, collection, or map.
new Object new(Object cls) Instantiates a class via its default constructor.
new1 Object new1(Object cls, Object arg) Instantiates a class with one constructor argument.
new2 Object new2(Object cls, Object arg1, Object arg2) Instantiates a class with two constructor arguments.
new3 Object new3(Object cls, Object arg1, Object arg2, Object arg3) Instantiates a class with three constructor arguments.
number Number number(Object value) Converts an object to a number.
parseDate Date parseDate(String source, String pattern) Parses a string into a Date with the given pattern.
parseNumber Number parseNumber(String source, String pattern) Parses a string into a number with the given pattern.
property String property(String key) Returns the value of the given library property, or null.
render void render(ActionContext ac) Renders a DSP fragment.
replace String replace(String src, String from, String to) Replaces all occurrences of from in src with to.
split String[] split(String value, String regex) Splits the string by the given regular expression.
startsWith boolean startsWith(String value, String prefix) Tests whether the string starts with the prefix.
string String toString(Object value) Converts an object to a string.
substring String substring(String s, int from, int to) Returns a substring of the given string.
testCurrentLocale boolean testCurrent(String lang, String country) Tests whether the current locale matches the language/country.
toLowerCase String toLowerCase(String value) Converts the string to lowercase using the current locale.
toUpperCase String toUpperCase(String value) Converts the string to uppercase using the current locale.
trim String trim(String value) Returns the string with leading and trailing whitespace removed.