utils.js
93 lines
| 1 | /** |
| 2 | * repr :: gets the string representation of `arg` |
| 3 | * @param {} arg :: unknown function argument |
| 4 | * @returns {String} :: a string representation of `arg` |
| 5 | */ |
| 6 | export const repr = (arg) => { |
| 7 | return Object.prototype.toString.call(arg); |
| 8 | }; |
| 9 | |
| 10 | /** |
| 11 | * isArray |
| 12 | * @param {} arg :: unknown function argument |
| 13 | * @returns {Boolean} :: returns true if `arg` is an Array, false otherwise |
| 14 | */ |
| 15 | export const isArray = (arg) => { |
| 16 | return Array.isArray ? Array.isArray(arg) : repr(arg) === "[object Array]"; |
| 17 | }; |
| 18 | |
| 19 | /** |
| 20 | * isObject :: checks if `arg` is an object. |
| 21 | * @param {} arg :: unknown function argument |
| 22 | * @returns {Boolean} :: returns true if `arg` is an object. |
| 23 | */ |
| 24 | export const isObject = (arg) => { |
| 25 | return repr(arg) === "[object Object]"; |
| 26 | }; |
| 27 | |
| 28 | /** |
| 29 | * isString :: checks if `arg` is a string. |
| 30 | * @param {} arg :: unknown function argument |
| 31 | * @returns {Boolean} :: returns true if `arg` is a String, false otherwise |
| 32 | */ |
| 33 | export const isString = (arg) => { |
| 34 | return repr(arg) === "[object String]"; |
| 35 | }; |
| 36 | |
| 37 | /** |
| 38 | * isNumber :: checks if `arg` is a number. |
| 39 | * @param {} arg :: unknown function argument |
| 40 | * @returns {Boolean} :: returns true if `arg` is a Number, false otherwise |
| 41 | */ |
| 42 | export const isNumber = (arg) => { |
| 43 | return repr(arg) === "[object Number]"; |
| 44 | }; |
| 45 | |
| 46 | export const isFloat = (n) => { |
| 47 | return Number(n) === n && n % 1 !== 0; |
| 48 | }; |
| 49 | |
| 50 | /** |
| 51 | * isNull :: checks if `arg` is null. |
| 52 | * @param {} arg :: unknown function argument |
| 53 | * @returns {Boolean} :: returns true if `arg` is of type Null, false otherwise |
| 54 | */ |
| 55 | export const isNull = (arg) => { |
| 56 | return repr(arg) === "[object Null]"; |
| 57 | }; |
| 58 | |
| 59 | /** |
| 60 | * isUndefined :: checks if `arg` is undefined. |
| 61 | * @param {} arg :: unknown function argument |
| 62 | * @returns {Boolean} :: Returns true if `arg` is of type Undefined, false otherwise |
| 63 | */ |
| 64 | export const isUndefined = (arg) => { |
| 65 | try { |
| 66 | return typeof arg === "undefined"; |
| 67 | } catch (e) { |
| 68 | if (e instanceof ReferenceError) { |
| 69 | return true; |
| 70 | } |
| 71 | |
| 72 | throw e; |
| 73 | } |
| 74 | }; |
| 75 | |
| 76 | /** |
| 77 | * isEmpty :: Checks if `arg` is an empty string, array, or object. |
| 78 | * |
| 79 | * @param {} arg :: unknown function argument |
| 80 | * @returns {Boolean} :: Returns true if `arg` is an empty string, |
| 81 | * array, or object. Also returns true is `arg` is null or |
| 82 | * undefined. Returns true otherwise. |
| 83 | */ |
| 84 | export const isEmpty = (arg) => { |
| 85 | return ( |
| 86 | isUndefined(arg) || |
| 87 | isNull(arg) || |
| 88 | (isString(arg) && arg.length === 0) || |
| 89 | (isArray(arg) && arg.length === 0) || |
| 90 | (isObject(arg) && Object.keys(arg).length === 0) |
| 91 | ); |
| 92 | }; |
| 93 |