Expression Functions Reference | Lightning Aura Components Developer Guide

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)` This function works for arguments of type `String`, `Decimal`, `Double`, `Integer`, `Long`, `Array`, `String[]`, `List`, and `Set`. Note	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.

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)` This function works for arguments of type `String`, `Array`, `Object`, `List`, `Map`, or `Set`. Note	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. `{! !empty(v.myArray)}` evaluates faster than `{!v.myArray && v.myArray.length > 0}` so we recommend `empty()` to improve performance. Tip The `$A.util.isEmpty()` method in JavaScript is equivalent to the `empty()` expression in markup.

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 syntax is awkward in markup so we recommend using the `and` function instead.
`or`	`or(hasPermission, hasVIPPass)`	Returns `true` if either one of the arguments is true.	`\|\|`
`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)