@tbosmans/typescript-utils

Conditionals

isArray

Checks if the given value is an array.

Specifications

• returns true when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns true when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isArray([1, 2, 3]); // true
isArray('hello world'); // false

isBlank

Checks if the given value is null or undefined.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns true when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns true when value is undefined

Examples

isBlank(null); // true
isBlank(undefined); // true
isBlank('hello world'); // false

isBoolean

Checks if the given value is a boolean.

Specifications

• returns false when value is array
• returns true when value is boolean false
• returns true when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isBoolean(true); // true
isBoolean(false); // true
isBoolean('hello world'); // false

isDate

Checks if the given value is a Date object.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns true when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isDate(new Date()); // true
isDate('2022-04-16'); // false

isDefined

Checks if the given value is not undefined.

Specifications

• returns true when value is array
• returns true when value is boolean false
• returns true when value is boolean true
• returns true when value is date
• returns true when value is empty array
• returns true when value is empty object
• returns true when value is empty string
• returns true when value is empty symbol
• returns true when value is negative number
• returns true when value is null
• returns true when value is number 0
• returns true when value is object
• returns true when value is positive number
• returns true when value is string
• returns true when value is symbol
• returns false when value is undefined

Examples

isDefined(null); // true
isDefined(undefined); // false
isDefined('hello world'); // true

isEmpty

Checks if the given value is empty.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns true when value is empty array
• returns true when value is empty object
• returns true when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isEmpty({}); // true
isEmpty([]); // true
isEmpty(''); // true
isEmpty({ name: 'John', age: 30 }); // false
isEmpty([1, 2, 3]); // false
isEmpty('hello world'); // false

isNull

Checks if the given value is null.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns true when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isNull(null); // true
isNull(undefined); // false
isNull('hello world'); // false

isNumber

Checks if the given value is a number.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns true when value is negative number
• returns false when value is null
• returns true when value is number 0
• returns false when value is object
• returns true when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isNumber(123); // true
isNumber('hello world'); // false

isObject

Checks if the given value is an object.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns true when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns true when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isObject({}); // true
isObject('hello world'); // false

isPresent

Checks if the given value is not null and not undefined.

Specifications

• returns true when value is array
• returns true when value is boolean false
• returns true when value is boolean true
• returns true when value is date
• returns true when value is empty array
• returns true when value is empty object
• returns true when value is empty string
• returns true when value is empty symbol
• returns true when value is negative number
• returns false when value is null
• returns true when value is number 0
• returns true when value is object
• returns true when value is positive number
• returns true when value is string
• returns true when value is symbol
• returns false when value is undefined

Examples

isPresent(null); // false
isPresent(undefined); // false
isPresent('hello world'); // true

isString

Checks if the given value is a string.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns true when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns true when value is string
• returns false when value is symbol
• returns false when value is undefined

Examples

isString('hello world'); // true
isString(123); // false

isSymbol

Checks if the given value is a symbol.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns true when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns true when value is symbol
• returns false when value is undefined

Examples

const mySymbol = Symbol('my symbol');
isSymbol(mySymbol); // true
isSymbol('hello world'); // false

isUndefined

Checks if the given value is undefined.

Specifications

• returns false when value is array
• returns false when value is boolean false
• returns false when value is boolean true
• returns false when value is date
• returns false when value is empty array
• returns false when value is empty object
• returns false when value is empty string
• returns false when value is empty symbol
• returns false when value is negative number
• returns false when value is null
• returns false when value is number 0
• returns false when value is object
• returns false when value is positive number
• returns false when value is string
• returns false when value is symbol
• returns true when value is undefined

Examples

isUndefined(undefined); // true
isUndefined(null); // false

Mutators

addOrRemove

Adds or removes the given value from an array, depending on whether it is already present or not. @param value The value to be added or removed.

Specifications

• add the value to the array when not included
• removes the value to the array when not included
• add the value to the array when not included
• removes the value to the array when not included

Examples

addOrRemove('hello', ['world']); // ['world', 'hello']
addOrRemove('world', ['world']); // []

Transformers

toDate

Converts a string to a Date object.

Specifications

• transforms 2020-03-02 into Date
• transforms 2020-03-02T23:00 into Date
• keeps null as null
• keeps undefined as undefined

Examples

toDate('2022-01-01'); // new Date('2022-01-01')
toDate(null); // null
toDate(undefined); // undefined
toDate(123); // Error: can't be cast to Date

toDateString

Converts a Date object to a string in YYYY-MM-DD format.

Specifications

• transforms 2020-03-02T0000.000Z into "2020-03-02"
• transforms 2022-01-01T2200.000Z into "2022-01-01"
• keeps null as null
• keeps undefined as undefined

Examples

const myDate = new Date('2022-01-01T00:00:00.000Z');
toDateString(myDate); // '2022-01-01'
toDateString(null); // null
toDateString(undefined); // undefined
toDateString('2022-01-01'); // Error: can't be cast to String date

toDateTimeString

Converts a Date object to a string in YYYY-MM-DDTHHss format.

Specifications

• transforms 2020-03-02T0000.000Z into "2020-03-02T0000"
• keeps null as null
• keeps undefined as undefined

Examples

const myDate = new Date('2022-01-01T00:00:00.000Z');
toDateTimeString(myDate); // '2022-01-01T00:00:00'
toDateTimeString(null); // null
toDateTimeString(undefined); // undefined
toDateTimeString('2022-01-01'); // Error: can't be cast to Date time string

toNumber

Converts a string, Date object, or boolean to a number.

Specifications

• transforms boolean false into string
• transforms boolean true into string
• transforms string into string
• transforms date into string
• keeps null as null
• keeps undefined as undefined

Examples

toNumber('123'); // 123
toNumber(new Date('2022-01-01T00:00:00.000Z')); // 1640995200000
toNumber(true); // 1
toNumber(null); // null
toNumber(undefined); // undefined
toNumber({}); // Error: can't be cast to number

toString

Converts a number, Date object, boolean, symbol, null, or undefined to a string.

Specifications

• transforms number into string
• transforms date into string
• transforms boolean false into string
• transforms boolean true into string
• transforms symbol into string
• keeps null as null
• keeps undefined as undefined

Examples

toString(123); // '123'
toString(new Date('2022-01-01T00:00:00.000Z')); // '2022-01-01T00:00:00.000Z'
toString(true); // 'true'
toString(null); // null
toString(undefined); // undefined
toString({}); // Error: can't be cast to string

toSymbol

Converts a string to a symbol.

Specifications

• transforms string into string
• keeps null as null
• keeps undefined as undefined

Examples

toSymbol('foo'); // Symbol('foo')
toSymbol(null); null
toSymbol(undefined); undefined
toSymbol(123); // Error: can't be cast to Symbol

toTimeString

Converts a Date object to a string time in the format HHss.

Specifications

• transforms 2020-03-02T0000.000Z into "0000"
• keeps null as null
• keeps undefined as undefined

Examples

toTimeString(new Date('2022-01-01T00:00:00.000Z')); // '00:00:00'
toTimeString(null); // null
toTimeString(undefined); // undefined
toTimeString('not a date'); // Error: can't be cast to time string