Package Exports
- js-flock
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Readme
js-flock
JS utility methods for NODE and Browser.
Including library
We can include whole library at once or a module by module. By default unmodified ES6 code is loaded, optionally we can load transpiled ES5 code. Transpiled code is wrapped in UMD and can be loaded in browser as CommonJs, AMD or as global var.
// Loads whole unmodified ES6 library
import jsFlock from 'js-flock';
// We can also use node require statement to do same thing
const jsFlock = require('js-flock');
// Loads single toEnum module. Ideal for usage in browser
import toEnum from 'js-flock/toEnum';
// Loads transpiled ES5 version of library
import jsFlock from 'js-flock/es5';
// Loads single transpiled module
import singular from 'js-flock/es5/singular';Methods:
toEnum
Convert object or list of strings to enum representation. Enum representation is immutable (frozen)
import toEnum from 'js-flock/toEnum';
const vehicleType = toEnum({
CAR: 'C',
TRUCK: 'T',
AIRPLANE: 'A',
HELICOPTER: 'H',
canFly(type) { // Define custom helper
return type === this.AIRPLANE || type === this.HELICOPTER;
}
});
const vehicle = getVehicle();
if (vehicle.type === vehicleType.TRUCK) {
// Special behaviour only for truck vehicles
}
if (vehicleType.canFly(vehicle.type)) {
// Special behaviour for vehicles that can fly
}
// enum is immutable
vehicleType.TRUCK = 'boat'; // vehicleType.TRUCK === 'T'
// Each enum have standard helpers
vehicleType.keys(); // ['CAR', 'TRUCK', 'AIRPLANE', 'HELICOPTER'] - helper functions are not included in keys
vehicleType.values(); // ['C', 'T', 'A', 'H']
vehicleType.exists('C'); // true
vehicleType.exists('something'); // false
vehicleType.haveKey('CAR'); // true
vehicleType.haveKey('something'); // false
// We can define enum with short notation. Limitation of short notation is that we can't define custom enum helpers.
const gender = toEnum(['MAN', 'WOMEN', 'OTHER']);
gender.keys(); // ['MAN', 'WOMEN', 'OTHER']
gender.values(); // [Symbol(MAN), Symbol(Women), Symbol(OTHER)]
sort
Small wrapper around sort to make sorting more readable and easier to write. Undefined and null values are always sorted to bottom of list no matter if ordering is ascending or descending.
import sort from 'js-flock/sort';
sort([1,4,2]).asc(); // sort array in ascending order [1, 2, 4]
sort([1,4,2]).desc(); // sort array in descending order [4, 2, 1]
// Sort persons (array of objects) ascending by lowercase names
sort(persons).asc((p) => p.name.toLowerCase());
// There is no exception if we try to sort values that are not sortable
// If input is not array same value is returned back
sort(null).asc(); // return null
sort(33).desc(); // return 33 sort(persons).asc((p) => p.name.toLowerCase());
// Above statement is equivalent to
persons.sort((a, b) => {
// == null are true for undefined and null.
// We need to check that first in order to move undefined/null values to bottom of list
if (a.name == null) return 1;
if (b.name == null) return -1;
// Cast to lowercase if there is value
const aName = aName.toLowerCase();
const bName = bName.toLowerCase();
if (aName === bName) return 0;
if (aName < bName) return -1; // Is this asc or desc sorting?? let's check documentation
return 1;
});singular
Creates singular function that after is called can't be called again until it finishes with execution. Singular function injects done function as a first argument of the original function. When called done indicates that function has finished with execution and that it can be called again.
For example we will use Vue.js and click handler.
<span @click="startConversation()" role="button"></span> export default {
methods: {
startConversation: singular(function(done) {
// After function is called all other calls will be ignored until done is called
if (this.conversation) { // Computed property that return conversation if exists
this.$store.dispatch('Chat/conversation/activate', this.conversation.channelId);
done(); // In this case done is called immediately
return;
}
// If conversation does not exist we need to create it in order to activate it
ChatService.conversation.createDirect(this.professor.id)
.then((newConversation) => {
this.$store.commit('Chat/conversation/add', newConversation);
this.$store.dispatch('Chat/conversation/activate', newConversation.channelId);
})
.catch((err) => {
Toast.showErrorToast();
this.$log.error(err);
})
.then(done); // In this case done is called asynchronously.
})
}
};promisify
Promisify error first callback function
const promisify = require('js-flock/promisify');
const readFile = require("fs").readFile;
const readFileAsync = promisify(readFile); // Promise version of read file
// Native version of read file
readFile('test.txt', 'utf8', (err, data) => {
if (err) {
return console.log(err);
}
console.log(data);
});
// Promisify version
readFileAsync('test.txt', 'utf8')
.then((data) => console.log(data))
.catch((err) => console.log(err));Promise resolve can return single parameter only. In order to resolve callbacks that are called with multiple parameters we can pass { multiArgs: true } option to promisify. When multiArgs are provided promise is always resolved with array even if callback is called with no arguments.
const fun = (cb) => cb(undefined, 'res1', 'res2');
const funAsync = promisify(fun, { multiArgs: true });
funAsync().then(([r1, r2]) => {
// r1 - res1
// r2 - res2
});collar
Set maximum waiting time for promise to resolve. Reject promise if it's not resolved in that time
import collar from 'js-flock/collar';
const MAX_WAIT_TIME = 500;
// Http request will be rejected if it's not resolved in 0.5 seconds
collar(Http.get('test-url'), MAX_WAIT_TIME)
.then((response) => console.log(response))
.catch((err) => console.log('promise have timed out'));
// Collar will reject promise chain as one of promises are not resolved in max time
collar(Promise.all([
new Promise((resolve) => setTimeout(resolve, 50, '1')),
new Promise((resolve) => setTimeout(resolve, 1000, '2'))
]), MAX_WAIT_TIME)
.then(() => { /* not called as second promise have timed out */ })
.catch((err) => { // CollarError = { isStrangled: true, message: 'Promises have timed out' }
if (typeof err === 'object' && err.isStrangled) {
console.log(err.message); // 'Promises have timed out'
}
});deepFreeze
Recursively apply Object.freez
import deepFreeze from 'js-flock/deepFreeze';
const person = {
fullName: 'test person',
dob: new Date(),
address: {
country: 'testiland',
city: 'this one'
}
}
Object.freeze(person);
Object.isFrozen(person); // true
Object.isFrozen(person.address); // false UH OH
deepFreeze(person);
Object.isFrozen(person); // true
Object.isFrozen(person.address); // true WE HEdeepSeal
Recursively apply Object.seal. For example check deepFreeze
