Binding Expressions Support

Scryber uses a Handlebars-style expression syntax ({{...}}) to bind data and execute functions within templates. This chart covers all supported helpers, operators, functions, and special variables.

All binding features are Scryber-specific — standard HTML has no equivalent built-in template engine.

On this page

Expression Syntax
Handlebars Helpers
Operators
Special Variables
Functions
Custom Functions & Operators
Common Patterns
See Also

Expression Syntax

Syntax	Example	Description
Output value	`{{model.name}}`	Renders a data value as text
Expression	`{{price * qty}}`	Evaluates an inline expression
Function call	`{{toUpper(model.name)}}`	Calls a built-in function
Conditional expression	`{{if(score >= 90, 'A', 'B')}}`	Inline ternary
CSS variable	`{{var(--theme-color)}}`	Reads a CSS custom property value
CSS calc	`{{calc(100% - 20pt)}}`	CSS calculation

Handlebars Helpers

Block-level helpers for control flow and iteration.

Helper	Syntax	Description
each	`{{#each items}}...{{/each}}`	Iterate over a collection; access current item with `{{this}}`
with	`{{#with object}}...{{/with}}`	Change the data context to a specific object
if	`{{#if condition}}...{{/if}}`	Conditional block; condition is any expression
else if	`{{else if condition}}`	Additional branch in an `if` block
else	`{{else}}`	Fallback branch when no condition is met
log	`{{log "message"}}`	Writes a debug message to the trace log

Operators

Used within {{expression}} bindings. Operator precedence follows standard mathematical rules.

Mathematical

Operator	Example	Description	Reference
`+`	`{{a + b}}`	Addition	→
`-`	`{{a - b}}`	Subtraction	→
`*`	`{{a * b}}`	Multiplication	→
`/`	`{{a / b}}`	Division	→
`%`	`{{a % b}}`	Modulus (remainder)	→
`^`	`{{a ^ b}}`	Power (exponentiation)	→

Comparison

Operator	Example	Description	Reference
`==`	`{{a == b}}`	Equality	→
`!=`	`{{a != b}}`	Inequality	→
`<`	`{{a < b}}`	Less than	→
`<=`	`{{a <= b}}`	Less than or equal	→
`>`	`{{a > b}}`	Greater than	→
`>=`	`{{a >= b}}`	Greater than or equal	→

Logical

Operator	Example	Description	Reference
`&&`	`{{a && b}}`	Logical AND	→
`\\|\\|`	`{{a \\|\\| b}}`	Logical OR	→
`!`	`{{!a}}`	Logical NOT

Operator	Example	Description	Reference
`.`	`{{model.address.city}}`	Property access
`[]`	`{{items[0]}}`	Array index access
`..`	`{{../parentValue}}`	Navigate to parent context
`??`	`{{value ?? 'default'}}`	Null coalescing — returns right side if left is null	→
`this`	`{{this.name}}`	Current context reference

Special Variables

Available automatically in specific contexts.

Variable	Context	Description
`@index`	`{{#each}}` loops	Zero-based index of the current item
`@first`	`{{#each}}` loops	`true` if this is the first item
`@last`	`{{#each}}` loops	`true` if this is the last item
`this`	Any	Current data context
`.`	Any	Shorthand for current context
`..`	Nested contexts	Parent context reference
`model`	Root	Root data model (from `doc.Params["model"]`)

Functions

Conversion

Function	Signature	Description
string	`string(value, format?)`	Convert to string with optional format
int	`int(value)`	Convert to 32-bit integer
long	`long(value)`	Convert to 64-bit integer
double	`double(value)`	Convert to double-precision float
decimal	`decimal(value)`	Convert to decimal number
bool	`bool(value)`	Convert to boolean
date	`date(value)`	Convert to DateTime
typeof	`typeof(value)`	Returns the type name as a string

String

Function	Signature	Description
concat	`concat(s1, s2, ...)`	Concatenate strings
join	`join(separator, array)`	Join array elements with a separator
substring	`substring(str, start, length?)`	Extract a portion of a string
replace	`replace(str, find, replace)`	Replace text in a string
toLower	`toLower(str)`	Convert to lowercase
toUpper	`toUpper(str)`	Convert to uppercase
trim	`trim(str)`	Remove whitespace from both ends
trimEnd	`trimEnd(str)`	Remove trailing whitespace
length	`length(str)`	Get string length
contains	`contains(str, search)`	Check if string contains text
startsWith	`startsWith(str, prefix)`	Check if string starts with prefix
endsWith	`endsWith(str, suffix)`	Check if string ends with suffix
indexOf	`indexOf(str, search)`	Find position of a substring
padLeft	`padLeft(str, len, char)`	Pad string on the left
padRight	`padRight(str, len, char)`	Pad string on the right
split	`split(str, separator)`	Split string into an array
format	`format(value, formatStr)`	Format value using a .NET format string
regexIsMatch	`regexIsMatch(str, pattern)`	Test if string matches a regex
regexMatches	`regexMatches(str, pattern)`	Return all regex matches
regexSwap	`regexSwap(str, pattern, replacement)`	Replace using a regex

Mathematical

Function	Signature	Description
abs	`abs(value)`	Absolute value
ceiling	`ceiling(value)`	Round up to nearest integer
floor	`floor(value)`	Round down to nearest integer
round	`round(value, decimals?)`	Round to nearest value
truncate	`truncate(value)`	Remove decimal portion
sqrt	`sqrt(value)`	Square root
pow	`pow(base, exponent)`	Raise to a power
exp	`exp(value)`	e raised to a power
log	`log(value)`	Natural logarithm
log10	`log10(value)`	Base-10 logarithm
sign	`sign(value)`	Returns -1, 0, or 1
sin	`sin(angle)`	Sine (radians)
cos	`cos(angle)`	Cosine (radians)
tan	`tan(angle)`	Tangent (radians)
asin	`asin(value)`	Arcsine
acos	`acos(value)`	Arccosine
atan	`atan(value)`	Arctangent
degrees	`degrees(radians)`	Convert radians to degrees
radians	`radians(degrees)`	Convert degrees to radians
pi	`pi()`	π constant (3.14159…)
e	`e()`	Euler’s number (2.71828…)
random	`random()`	Random value between 0 and 1

Date & Time

Function	Signature	Description
addDays	`addDays(date, n)`	Add days to a date
addMonths	`addMonths(date, n)`	Add months to a date
addYears	`addYears(date, n)`	Add years to a date
addHours	`addHours(date, n)`	Add hours to a date
addMinutes	`addMinutes(date, n)`	Add minutes to a date
addSeconds	`addSeconds(date, n)`	Add seconds to a date
addMilliseconds	`addMilliseconds(date, n)`	Add milliseconds to a date
daysBetween	`daysBetween(d1, d2)`	Days between two dates
hoursBetween	`hoursBetween(d1, d2)`	Hours between two dates
minutesBetween	`minutesBetween(d1, d2)`	Minutes between two dates
secondsBetween	`secondsBetween(d1, d2)`	Seconds between two dates
yearOf	`yearOf(date)`	Extract the year
monthOfYear	`monthOfYear(date)`	Extract the month (1–12)
dayOfMonth	`dayOfMonth(date)`	Extract the day of month
dayOfWeek	`dayOfWeek(date)`	Extract the day of week
dayOfYear	`dayOfYear(date)`	Extract the day of year (1–365)
hourOf	`hourOf(date)`	Extract the hour (0–23)
minuteOf	`minuteOf(date)`	Extract the minute (0–59)
secondOf	`secondOf(date)`	Extract the second (0–59)
millisecondOf	`millisecondOf(date)`	Extract the millisecond (0–999)

Logical

Function	Signature	Description
if	`if(condition, trueVal, falseVal)`	Ternary conditional
ifError	`ifError(expression, fallback)`	Return fallback if expression throws
in	`in(value, a, b, ...)`	Check if value exists in a list

Collection

Function	Signature	Description
count	`count(array)`	Count elements
countOf	`countOf(array)`	Alias for `count()`
sum	`sum(array)`	Sum numeric values
sumOf	`sumOf(array, 'prop')`	Sum a property across elements
min	`min(array)`	Minimum value
minOf	`minOf(array, 'prop')`	Minimum of a property
max	`max(array)`	Maximum value
maxOf	`maxOf(array, 'prop')`	Maximum of a property
collect	`collect(expr, array)`	Map an expression over an array
each	`each(array)`	Iterate over array (returns array)
firstWhere	`firstWhere(array, condition)`	First matching element
selectWhere	`selectWhere(array, condition)`	Filter array by condition
sortBy	`sortBy(array, 'prop')`	Sort by property
reverse	`reverse(array)`	Reverse array order

Statistical

Function	Signature	Description
average	`average(array)`	Mean of array values
averageOf	`averageOf(array, 'prop')`	Mean of a property
mean	`mean(array)`	Alias for `average()`
median	`median(array)`	Middle value
mode	`mode(array)`	Most common value

CSS / Document

Function	Signature	Description
calc	`calc(expression)`	CSS calculation (prefer inline operators)
var	`var(--name)`	Read a CSS custom property value

Custom Functions & Operators

The binding system can be extended with custom functions and operators registered at startup:

// Register a custom function
BindingCalcExpressionFactory.RegisterFunction(new MyCustomFunction());

// Register a custom operator
BindingCalcExpressionFactory.RegisterOperator(new MyCustomOperator());

See the Configuration section for more on extending Scryber.

Common Patterns

Format a currency value:

{{format(model.price, 'C2')}}

Format a date:

{{format(orderDate, 'yyyy-MM-dd')}}

Conditional class:

<div class="{{if(isActive, 'active', 'inactive')}}">

Null-safe navigation:

{{user.address.city ?? 'No city'}}

Sum a collection property:

Total: {{format(sumOf(items, .price), 'C2')}}

Loop with index:

{{#each items}}
  <p>{{@index}}. {{this.name}}</p>
{{/each}}

Binding Expressions Support

Expression Syntax

Handlebars Helpers

Operators

Mathematical

Comparison

Logical

Navigation & Null Handling

Special Variables

Functions

Conversion

String

Mathematical

Date & Time

Logical

Collection

Statistical

CSS / Document

Custom Functions & Operators

Common Patterns

See Also