$calc

The $calc function is a powerful expression evaluator that enables complex calculations, string manipulations, array operations, and provides a secure sandbox environment within your templates.

Basic Usage

{{$calc "5 + 3"}}              {{!-- outputs: 8 --}}
{{$ "5 + 3"}}                  {{!-- shorthand syntax --}}

Output Types

The function can return different types of values:

• Numbers: Mathematical calculations, statistical results

• Strings: Text manipulation results

• Arrays: Collection operations

• Booleans: Conditional evaluations

• Empty String: Returned for null/undefined values or errors

Variable Interpolation

Use {variableName} syntax to reference context variables:

Template

{{$calc "{price} * 1.2"}}      {{!-- outputs: 120 --}}
{{$calc "{user.age} + 5"}}     {{!-- outputs: 30 --}}

Data

Storing Results

You can store calculation results for later use using the $var function:

Template

{{$var "tax_amount" ($calc "{price} * 0.2")}}
{{!-- Later in the template --}}
Total with tax: {{$calc "{price} + {tax_amount}"}}

Data

Formatting Options

Decimal Places

{{$calc "100 / 3" decimals=2}}  {{!-- outputs: 33.33 --}}

Custom Number Format (using number formatter patterns)

{{$calc "1234.5" format="0,0.00"}}  {{!-- outputs: 1,234.50 --}}
{{$calc "0.123" format="0.00%"}}    {{!-- outputs: 12.30% --}}

Error Handling

{{$calc "10/0" error="Division Error"}}  {{!-- outputs: "Division Error" --}}

Function Reference

Mathematical Functions

Basic Arithmetic

• Addition (+), Subtraction (-), Multiplication (*), Division (/), Modulo (%)

{{$calc "5 + 3"}}              {{!-- addition: 8 --}}
{{$calc "5 - 3"}}              {{!-- subtraction: 2 --}}
{{$calc "5 * 3"}}              {{!-- multiplication: 15 --}}
{{$calc "15 / 3"}}             {{!-- division: 5 --}}
{{$calc "5 % 2"}}              {{!-- modulo: 1 --}}

Advanced Math Functions

• abs(x): Returns absolute value of x

{{$calc "abs(-5)"}}            {{!-- absolute value: 5 --}}

• max(...args): Returns largest value among arguments

{{$calc "max(1, 2, 3)"}}       {{!-- maximum value: 3 --}}

• min(...args): Returns smallest value among arguments

{{$calc "min(1, 2, 3)"}}       {{!-- minimum value: 1 --}}

• pow(base, exp): Returns base raised to exp power

{{$calc "pow(2, 3)"}}          {{!-- power: 8 --}}

• sqrt(x): Returns square root of x

{{$calc "sqrt(16)"}}           {{!-- square root: 4 --}}

• round(x): Rounds to nearest integer

{{$calc "round(3.7)"}}         {{!-- round: 4 --}}

• ceil(x): Rounds up to nearest integer

{{$calc "ceil(3.2)"}}          {{!-- ceiling: 4 --}}

• floor(x): Rounds down to nearest integer

{{$calc "floor(3.8)"}}         {{!-- floor: 3 --}}

String Operations

• lower(str): Converts string to lowercase

{{$calc 'lower("HELLO")'}}     {{!-- lowercase: "hello" --}}

• upper(str): Converts string to uppercase

{{$calc 'upper("hello")'}}     {{!-- uppercase: "HELLO" --}}

• trim(str): Removes leading/trailing whitespace

{{$calc 'trim(" hello ")'}}    {{!-- trim whitespace: "hello" --}}

• concat(...args): Joins all arguments into single string

{{$calc 'concat("a", "b")'}}   {{!-- concatenate: "ab" --}}

• slice(str, start, end): Extracts portion of string

{{$calc 'slice("hello", 0, 2)'}} {{!-- slice string: "he" --}}

• replace(str, search, replace): Replaces first occurrence of search with replace

{{$calc 'replace("hello", "l", "w")'}} {{!-- replace: "hewlo" --}}

Array Operations

• arr(...args): Creates array from arguments

{{$calc "arr(1, 2, 3)"}}       {{!-- create array: [1, 2, 3] --}}

• first(arr): Returns first element

{{$calc "first([1, 2, 3])"}}   {{!-- first element: 1 --}}

• last(arr): Returns last element

{{$calc "last([1, 2, 3])"}}    {{!-- last element: 3 --}}

• len(arr): Returns array length

{{$calc "len([1, 2, 3])"}}     {{!-- array length: 3 --}}

• join(arr, separator, finalSeparator): Joins array elements with optional custom separators

{{$calc 'join(["a","b"], ",")'}} {{!-- join array: "a,b" --}}

• split(str, separator): Splits string into array

{{$calc 'split("a,b", ",")'}}  {{!-- split string: ["a", "b"] --}}

• sort(arr): Returns sorted array

{{$calc "sort([3, 1, 2])"}}    {{!-- sort array: [1, 2, 3] --}}

• reverse(arr): Returns reversed array

{{$calc "reverse([1, 2, 3])"}} {{!-- reverse array: [3, 2, 1] --}}

Statistical Functions

• avg(...nums): Calculates average of numbers

{{$calc "avg(1, 2, 3)"}}       {{!-- average: 2 --}}

• med(nums): Calculates median of array

{{$calc "med([1, 3, 2])"}}     {{!-- median: 2 --}}

• sum(nums, [prop]): Sums array elements, optionally extracting property from objects

{{$calc "sum([1, 2, 3])"}}     {{!-- sum: 6 --}}

{{!-- Sum with object arrays --}}
{{$calc 'sum([{val: 1}, {val: 2}], "val")'}}  {{!-- sum of val property: 3 --}}

Type Conversion

• str(val): Converts to string

{{$calc 'str(123)'}}           {{!-- to string: "123" --}}

• num(val): Converts to number

{{$calc 'num("123")'}}         {{!-- to number: 123 --}}

• bool(val): Converts to boolean

{{$calc 'bool(1)'}}            {{!-- to boolean: true --}}

Complex Examples

Data Processing Pipeline

{{!-- Store processed data for later use --}}
{{$var "processed_data" ($calc 'join(sort(arr(concat(upper("hello"), ":", str(sum([1,2,3]))),concat(lower("WORLD"), ":", str(avg(2,4,6)))))," | ")')}}

{{!-- Output: "HELLO:6 | world:4" --}}
{{processed_data}}

Complex Conditional Calculation

{{$calc 'if(len({items}) > 0) then concat("Items: ", join(sort(arr(concat(upper(first({items})), "-", str(sum({values}))), concat(lower(last({items})), "-", str(avg({values})))) ), " | ")) else "No items available"   endif'}}

Limitations and Safety Features

• Maximum number size: 1e15

• Maximum array length: 1000

Best Practices

• Store intermediate calculations using $var for complex operations

• Use appropriate formatting options for consistent output

• Handle potential errors with the error option

• Break complex calculations into smaller parts

• Use meaningful variable names

• Consider performance with large arrays

• Validate user input before processing

• Use comments to document complex expressions