_.util.existential.js.md

util.existential

Functions which deal with whether a value “exists.”

exists

Signature: _.exists(value:Any)

Checks whether or not the value is “existy.” Both null and undefined are considered non-existy values. All other values are existy.

_.exists(null);
// => false

_.exists(undefined);
// => false

_.exists({});
// = > true

_.exists("Sparta");
// => true

falsey

Signature: _.falsey(value:Any)

Checks whether the value is falsey. A falsey value is one which coerces to false in a boolean context.

_.falsey(0);
// => true

_.falsey("");
// => true

_.falsey({});
// => false

_.falsey("Corinth");
// => false

firstExisting

Signature: _.firstExisting(value:Any[, value:Any...])

Returns the first existy argument from the argument list.

_.firstExisting("Socrates", "Plato");
// => "Socrates"

_.firstExisting(null, undefined, "Heraclitus");
// => "Heraclitus"

not

Signature: _.not(value:Any)

Returns a boolean which is the opposite of the truthiness of the original value.

_.not(0);
// => true

_.not(1);
// => false

_.not(true);
// => false

_.not(false);
// => true

_.not({});
// => false

_.not(null);
// => true

truthy

Signature: _.truthy(value:Any)

Checks whether the value is truthy. A truthy value is one which coerces to true in a boolean context.

_.truthy({});
// => true

_.truthy("Athens");
// => true

_.truthy(0);
// => false

_.truthy("");
// => false