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Expressions

Expressions let Jess evaluate values explicitly.

Write an expression as $(...).

  • $var is a variable Reference (not an Expression).
  • $(...) is an Expression.

Inside an expression, keep variable references explicit: $($var).

Examples​

Basic arithmetic​

value: $(1 + 2); // 3
value: $(1 - 2); // -1
value: $(1 * 2); // 2
value: $(1 / 2); // 0.5
value: $(1 % 2); // 1 (modulus)

CSS values​

value: $(#222 / 2); // #111

Jess variables​

$width: 10px;
$height: $($width + 10px);

#header {
  width: $width;
  height: $height;
}

References vs expressions​

Inside an expression, a plain identifier is a value or keyword. A variable still uses its $ sigil.

$color: red;
value: $(red); // red (color keyword literal)
value: $($color); // red (variable reference inside Expression)
value: $less.iscolor($color); // true
$num: 10;
value: $($num + 1); // 11

Arithmetic is explicit​

Keep arithmetic inside the expression wrapper:

$w: 10px;
width: $($w + 1px);

Use a variable reference inside the expression. Do not write unwrapped arithmetic such as $w + 1px.