@fujitsusweden/futile

Fujitsu Sweden Utils

What is it

A utility library, mainly used by other packages by Fujitsu Sweden.

Usage

const futile = require("@fujitsusweden/futile");

futile.canonize(value)

> futile.canonize({ c: { d: 1, a: 2 }, b: 3, e: 4 })
'{"b":3,"c":{"a":2,"d":1},"e":4}'

Like JSON.stringify except object keys are sorted. This serialization is JSON compatible, meaning that _.isEqual(a, JSON.parse(futile.canonize(a))) is always true, just like _.isEqual(a, JSON.parse(JSON.stringify(a))). It also provides a canonization, meaning that futile.canonize(a) === futile.canonize(b) if and only if _.isEqual(a, b). Note that JSON.stringify does not provide a canonization w.r.t. _.isEqual. For example, futile.canonize({ a:1, b:2 }) === futile.canonize({ b:2, a:1 }) but JSON.stringify({ a:1, b:2 }) !== JSON.stringify({ b:2, a:1 }). One use case for a canonizing serialization is property names for indexing on the contents of objects.

futile.deepFreeze(value)

Recursive variant of Object.freeze().

Example:

> o = deepFreeze({ a: { b: "ORIGINAL" }, c: 2 });
{ a: { b: "ORIGINAL" }, c: 2 };
> o.a.b = "changed";
"changed";
> o;
{ a: { b: "ORIGINAL" }, c: 2 };

Note that

• The change to read-only properties is destructive, i.e. the argument to futile.deepFreeze is altered. If you want to keep a changeable version around, use _.cloneDeep first.
• In strict mode, assigning to a read-only property as in the example above will throw an error.

futile.diffIntDiff(data1, data2)

A fast way to compute [_.differenceWith(data1, data2, _.isEqual), _.intersectionWith(data1, data2, _.isEqual), _.differenceWith(data2, data1, _.isEqual)].

In other words, given two lists of values, use the same definition of equality as _.isEqual and compute

• A list of values only found in the first source list
• A list of values found in both source lists
• A list of values only found in the second source list

futile.err(message, object)

Makes it easier to pass meta-data in an error.

throw futile.err("Error message", { metadata1: value1, otherthing2: value2 })

futile.indexBy(collection, keyfun)

Given an array or other collection, return a plain object with values from the collection and keys calculated using keyfun. If keyfun is a string, it is treated as a function that returns the property by that name.

Example:

> const data = [{ id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }];
undefined
> futile.indexBy(data, 'name')
{ Alice: { id: 1, name: 'Alice' }, Bob: { id: 2, name: 'Bob' } }
> futile.indexBy(data, x => `_${x.id}`)
{ _1: { id: 1, name: 'Alice' }, _2: { id: 2, name: 'Bob' } }

futile.interval(intervalString)

Convert a temporal interval from a string representation to the number of milliseconds as an integer. Supported units are ms, s, min, h.

> futile.interval('5 s')
5000
> futile.interval('2 min')
120000

futile.now()

Returns a date object that represents now.

futile.reqMock(hint)

Return an object similar to an ExpressJS req object.

futile.since(date)

Returns the number of milliseconds between date and now.

futile.sleep(delay)

Asynchronous delay function. Accepts delay in milliseconds or in futile.interval format.

Example to wait 5 seconds:

await futile.sleep('5 s');

futile.xor(...args)

Returns true if an odd number of arguments are truthy, otherwise false.

Development

Run ./script without arguments for help