TypoScript syntax comes with a couple of operators to assign values, copy from other identifier paths, and to manipulate values. Let's have a closer look at them.

Value assignment with "="

This most common operator assigns a single line value to an identifier path. Everything after the = character until the end of the line is considered to be the value. The value is trimmed, leading and trailing whitespaces are removed.

Values are parsed for constant references. With a value assignment like foo = someText {$someConstant} furtherText, the parser will look up the constant reference {$someConstant} and tries to substitute it with a defined constant value. If such a constant does not exist, it falls back to the string literal including the {$ and } characters.

A couple of examples:

Multiline assignment with "(" and ")"

Opening and closing parenthesis are used to assign multi-line values. This allows defining values that span several lines and thus include line breaks.

The end parenthesis ) is important: If it is not found, the parser considers all following lines until the end of the TypoScript text snipped to be part of the value. This includes comments, [GLOBAL] conditions and @import file includes: They are not a syntax construct and are considered part of the value assignment.

However, the value is parsed for constants (text looking like {$myIdentifier.mySubIdentifier}: The parser will try to substitute them to their assigned constant value. The "TypoScript" and "Page TSconfig" backend modules may show a warning if a reference to a constant can't be resolved. If a constant reference can't be resolved, the value falls back to its string literal. Since multi-line values are sometimes used to output JavaScript, and JavaScript also uses a syntax construct like {$...}, this may lead to false positive warnings in those backend modules.

A couple of examples:

Unset with ">"

This can be used to unset a previously defined identifier path value, and all of its sub identifiers:

Copy with "<"

The < character is used to copy one identifier path to another. The whole current identifier state is copied: both value and sub identifiers. It overrides any old sub identifiers and values at that position.

The copy operator is useful to follow the DRY - Don't repeat yourself principle. It allows maintaining a configuration set at a central place, and copies are used at further places when needed again.

The result of the below TypoScript is two independent sets which are duplicates. They are not references to each other but actual copies:

The copy operator is allowed within code blocks as well:

In the above example, the copied identifier path is referred to with its full path myIdentifier.10. When copying on the same level, it is allowed to use a relative path, indicated by a prepended dot. The following produces the same result as above:

Using the copy operator creates a copy of the source path at exactly this point in the parsing process. Changing the source afterwards does not change the target, and changing the target afterwards does not change the source:

References with "=<"


The reference operator =< is not a general syntax construct. Even though the TypoScript and TSconfig backend modules show usages of the operator, they are only resolved in frontend TypoScript for the special tt_content path: You can use =< in frontend TypoScript for example with tt_content.text =< lib.contentElement, and you are encouraged to do so in this special case for performance reasons, but this operator does not work anywhere else.

In the context of frontend TypoScript, it is possible to create references from one identifier path to another within the tt_content path. References mean that multiple positions can copy the same source identifier path without making an actual copy. This allows changes to the source identifier afterwards, which changes the targets as well. References can be convenient for this special case, but should be used with caution.

Value modifications with ":="

This operator assigns a value to an identifier path by calling a predefined function which modifies the existing value in different ways. This is very useful when a value should be modified without completely redefining it again.

A modifier is referenced by its modifier name, plus arguments in parenthesis. These predefined functions are available:

  • prependString()

    Add a string to the beginning of the existing value.

    foo = cd
    foo := prependString(ab)
    # foo is "abcd"
  • appendString()

    Add a string to the end of the existing value.

    foo = ab
    foo := appendString(cd)
    # foo is "abcd"
  • removeString()

    Remove a string from the existing value.

    foo = foobarfoo
    foo := removeString(foo)
    # foo is "bar"
  • replaceString()

    Replace old with new value. Separate these using |.

    foo = abcd
    foo := replaceString(bc|123)
    # foo is "a123d"
  • addToList()

    Add values to the end of a list of existing values. There is no check for duplicate values, and the list is not sorted in any way.

    foo = 123,456
    foo := addToList(789)
    # foo is "123,456,789"
    foo =
    foo := addToList(123)
    # foo is "123" (no leading comma added on empty existing value)
  • removeFromList()

    Remove a comma-separated list of values from an existing comma-separated list of values. Empty values are removed as well.

    foo = foo,123,bar,456,foo,,789
    foo:= removeFromList(foo,bar)
    # foo is "123,456,789"
  • uniqueList()

    Remove duplicate entries from a comma-separated list of values.

    foo = 123,456,abc,456,456
    foo := uniqueList()
    # foo is "123,456,abc"
  • reverseList()

    Reverses the order of entries in a comma-separated list of values.

    foo = 123,456,abc,456
    foo := reverseList()
    # foo is "456,abc,456,123"
  • sortList()

    Sorts the entries in a comma-separated list of values. There are optional sorting parameters, multiple can be separated using ,:

    ascending (default)

    Sort the items in ascending order: First numbers from small to big, then letters in alphabetical order.


    Sort the items in descending order: First letters in descending order, then numbers from big to small.


    Apply numeric sorting: Numbers from small to big, letters sorted after "0".

    foo = 10,100,0,20,abc
    foo := sortList()
    # foo is "0,10,20,100,abc"
    foo = 10,0,100,-20
    foo := sortList(numeric)
    # foo is "-20,0,10,100"
    foo = 10,100,0,20,-20
    foo := sortList(numeric,descending)
    # foo is "100,20,10,0,-20"
  • getEnv()

    Access a $_ENV value. Resolves to empty value if not set.

    # $_ENV['foo'] = 'fooValue'
    foo := getEnv(foo);
    # foo is "fooValue"
  • "myCustomFunction()"

    Changed in version 12.0.

    The PSR-14 event \TYPO3\CMS\Core\TypoScript\AST\Event\EvaluateModifierFunctionEvent is available to define custom TypoScript functions. The event replaces the hook $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tsparser.php']['preParseFunc'].

    The section EvaluateModifierFunctionEvent provides an example and the API.