# Expression Functions Reference The expression language contains math, string, array, comparison, boolean, and conditional functions. All functions are case-sensitive. ## Math Functions The math functions perform math operations on numbers. They take numerical arguments. The Corresponding Operator column lists equivalent operators, if any. | Function | Alternative | Usage | Description | Corresponding Operator | | -------- | ----------- | ------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------- | | `add` | `concat` | `add(1,2)` | Adds the first argument to the second. | `+` | | `sub` | `subtract` | `sub(10,2)` | Subtracts the second argument from the first. | `-` | | `mult` | `multiply` | `mult(2,10)` | Multiplies the first argument by the second. | `*` | | `div` | `divide` | `div(4,2)` | Divides the first argument by the second. | `/` | | `mod` | `modulus` | `mod(5,2)` | Returns the integer remainder resulting from dividing the first argument by the second. | `%` | | `abs` |   | `abs(-5)` | Returns the absolute value of the argument: the same number if the argument is positive, and the number without its negative sign if the number is negative. For example, `abs(-5) is 5`. | None | | `neg` | `negate` | `neg(100)` | Reverses the sign of the argument. For example, `neg(100) is -100`. | `-` (unary) | ## String Functions | Function | Alternative | Usage | Description | Corresponding Operator | | -------- | ----------- | ----------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | ---------------------- | | `concat` | `add` | `concat('Hello ', 'world')``add('Walk ', 'the dog')` | Concatenates the two arguments. | `+` | | `format` |   | `format($Label.ns.labelName, v.myVal)` | Replaces any parameter placeholders with comma-separated attribute values. |   | | `join` |   | `join(separator, subStr1, subStr2, subStrN)``join(' ','class1', 'class2', v.class)` | Joins the substrings adding the separator String (first argument) between each subsequent argument. |   | :::note The `format` function works for arguments of type `String`, `Decimal`, `Double`, `Integer`, `Long`, `Array`, `String[]`, `List`, and `Set`. ::: ## Label Functions | Function | Usage | Description | | -------- | ------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `format` | `format($Label.np.labelName, v.attribute1 , v.attribute2)``format($Label.np.hello, v.name)` | Outputs a label and updates it. Replaces any parameter placeholders with comma-separated attribute values. Supports ternary operators in labels and attributes. | ## Informational Functions | Function | Usage | Description | | | | -------- | ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | - | - | | `length` | `myArray.length` | Returns the length of an array or a string. |   |   | | `empty` | `empty(v.attributeName)` | Returns `true` if the argument is empty. An empty argument is `undefined`, `null`, an empty array, or an empty string. An object with no properties is not considered empty. The `$A.util.isEmpty()` method in JavaScript is equivalent to the `empty()` expression in markup. |   |   | :::note The `empty` function works for arguments of type `String`, `Array`, `Object`, `List`, `Map`, or `Set`. ::: :::tip `{! !empty(v.myArray)}` evaluates faster than `{!v.myArray && v.myArray.length > 0}` so we recommend `empty()` to improve performance. ::: ## Comparison Functions Comparison functions take two number arguments and return `true` or `false` depending on the comparison result. The `eq` and `ne` functions can also take other data types for their arguments, such as strings. | Function | Usage | Description | Corresponding Operator | | -------------------- | ------------------------- | -------------------------------------------------------------------------------------------------- | ---------------------- | | `equals` | `equals(1,1)` | Returns `true` if the specified arguments are equal. The arguments can be any data type. | `==` or `eq` | | `notequals` | `notequals(1,2)` | Returns `true` if the specified arguments are not equal. The arguments can be any data type. | `!=` or `ne` | | `lessthan` | `lessthan(1,5)` | Returns `true` if the first argument is numerically less than the second argument. | `<` or `lt` | | `greaterthan` | `greaterthan(5,1)` | Returns `true` if the first argument is numerically greater than the second argument. | `>` or `gt` | | `lessthanorequal` | `lessthanorequal(1,2)` | Returns `true` if the first argument is numerically less than or equal to the second argument. | `<=` or `le` | | `greaterthanorequal` | `greaterthanorequal(2,1)` | Returns `true` if the first argument is numerically greather than or equal to the second argument. | `>=` or `ge` | ## Boolean Functions Boolean functions operate on Boolean arguments. They are equivalent to logical operators. | Function | Usage | Description | Corresponding Operator | | -------- | ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | `and` | `and(isEnabled, hasPermission)` | Returns `true` if both arguments are true. This function supports only two arguments. Any arguments after the first two are ignored. | `&&` This syntax is awkward in markup so we recommend using the `and()` function instead when you have two arguments. If you have more than two arguments, you can chain multiple `&&` operations. | | `or` | `or(hasPermission, hasVIPPass)` | Returns `true` if either one of the arguments is true. This function supports only two arguments. Any arguments after the first two are ignored. | `\|\|` If you have more than two arguments, you can chain multiple `\|\|` operations. | | `not` | `not(isNew)` | Returns `true` if the argument is false. | `!` | ## Conditional Function | Function | Usage | Description | Corresponding Operator | | -------- | ----------------------------------------- | ----------------------------------------------------------------------------------------------------------------------- | ---------------------- | | `if` | `if(isEnabled, 'Enabled', 'Not enabled')` | Evaluates the first argument as a boolean. If true, returns the second argument. Otherwise, returns the third argument. | `?:` (ternary) |