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isLesser()

isLesser<T>(threshold): (value) => boolean

Creates a predicate function that determines if a value is less than a threshold.

Type Parameters​

T​

T extends string | number

The type of the values (number or string)

Parameters​

threshold​

T

The threshold value to compare against

Returns​

(value): boolean

Parameters​

value​

T

Returns​

boolean

Remarks​

  • Pure function with no side effects
  • Uses JavaScript's < operator for comparison
  • Works with both numbers and strings (lexicographic comparison for strings)
  • Useful for array filtering and functional composition

Example​

const isBelowLimit = isLesser(100);
isBelowLimit(50);  // true
isBelowLimit(150); // false

const isBeforeM = isLesser('M');
isBeforeM('A'); // true
isBeforeM('Z'); // false

// Useful with arrays
const temperatures = [15, 25, 35, 45];
const cool = temperatures.filter(isLesser(30)); // [15, 25]