is - dejs @ ウィキ

is(Value): try to return Value.constructor

returning Function || null || undefined

Basically "is[methods]" are matching value of type

returning Boolean;

• is.array(Value);
• is.object(Value);
• is.function(Value);
• is.boolean(Value);
• is.string(Value);
• is.number(Value);
• is.symbol(Value);
• is.null(Value);
• is.defined(Value): is Value not undefined;

Applicably "is[methods]" are useful case;

returning Boolean;

• is.blank(Value): If Value is blank string, return true;
• is.pure(Value): If Value is Object or Array, return true;
• is.nan(Value): If Value is primitive Number but Value is NaN, return true;
• is.self(Proto): If Proto is Proto.constructor.prototype, return true;
• is.valid(Value): If Value is held any value, return true;
• is.there(AO): If Array or Object is held something, return true;
• is.held(Value)(Super): If Value is instance of Super, return true;