Number

Numbers in Sessel represent numeric values — integers and decimals. Both types interoperate seamlessly in expressions; you rarely need to distinguish between them.

Literal syntax

42
3.14
-7

Arithmetic operators

${[itemprop="price"]}.sum() / ${[itemprop="price"]}.count()

(${[itemprop="subtotal"]}.sum() + 5) * 1.1

Integer division of two integers returns an integer (truncating toward zero). When either operand is a float, the result is a float: 10 / 4 produces 2, but 10.0 / 4 produces 2.5.

Comparison operators

Numbers support all six comparison operators plus the spaceship operator. Comparison results are booleans; the spaceship result is an integer.

${div.item}.count() > 3
${[itemprop="price"]}.sum() >= 100
${[itemprop="stock"]}.first().value().Integer() == 0

The spaceship operator <=> is primarily useful in sort comparator lambdas:

${li}.sort((a, b) => a.text().Number() <=> b.text().Number())

Methods

.String()

Converts a number to its string representation.

${div.item}.count().String()

Returns: string

Useful when a template or string method requires a string rather than a number.

.abs()

Returns the absolute value of a number.

(-5).abs()      // 5
5.abs()         // 5
(-3.14).abs()   // 3.14

Returns: the same numeric type (integer stays integer, float stays float).

.floor()

Rounds a number down toward negative infinity. Integer values are returned unchanged. Float values are rounded down and returned as integers.

3.7.floor()      // 3
(-3.2).floor()   // -4
42.floor()       // 42

Returns: integer

.ceil()

Rounds a number up toward positive infinity. Integer values are returned unchanged. Float values are rounded up and returned as integers.

3.2.ceil()       // 4
(-3.7).ceil()    // -3
42.ceil()        // 42

Returns: integer

.round()

Rounds a number to the nearest integer, with ties rounding away from zero. Integer values are returned unchanged.

3.5.round()      // 4
3.4.round()      // 3
(-3.5).round()   // -4
42.round()       // 42

Returns: integer

How numbers arise

Numbers appear in Sessel expressions from several sources:

Literals

42 + 8

Coercion from strings — coercion methods that parse numeric content:

${[itemprop="price"]}.first().value().Number()
${[itemprop="quantity"]}.first().value().Integer()
${[itemprop="rating"]}.first().value().Float()

Only .Number() returns null if the string cannot be parsed — .Integer() and .Float() throw a type error instead. Use ?? to provide a fallback on .Number():

${[itemprop="price"]}.first().value().Number() ?? 0

List aggregation methods — these operate on a list of elements and return a number:

.sum(), .min(), and .max() preserve the integer type when all inputs are integers. If any input is a float, the result is a float.

String length — .count() on a string returns the number of characters:

${h1}.first().text().count()

Number coercion

Coercion methods convert between number subtypes:

"42".Number()       // 42 (integer)
"3.14".Number()     // 3.14 (float)
3.14.Integer()      // 3
42.Float()          // 42.0

Random number generation

Type namespaces provide static random() methods for generating random numbers.

Integer.random(min, max)

Returns a random integer in the inclusive range [min, max]. Both arguments must be integers.

Integer.random(1, 6)          // a random die roll: 1, 2, 3, 4, 5, or 6
Integer.random(0, 100)        // a random integer from 0 to 100 inclusive

Float.random(min, max)

Returns a random float in the half-open range [min, max). Both arguments must be numeric.

Float.random(0.0, 1.0)        // a random float in [0.0, 1.0)
Float.random(1, 10)           // integer args are promoted to float

Number.random(min, max)

Infers the return type from argument types. If both arguments are integers, returns an integer. If either is a float, returns a float.

Number.random(1, 10)          // integer result (both args are integer)
Number.random(1.0, 10.0)      // float result (both args are float)
Number.random(1, 10.0)        // float result (mixed args)

Range validation: if min > max, the bounds are silently swapped. If min == max, min is returned directly.

See also

• String — string type and coercion methods
• Types — overview of all Sessel types and their methods
• Syntax — operators and operator precedence