ast-loose-compare^1.9.1

§ Quick Take

import { strict as assert } from "assert";
import looseCompare from "ast-loose-compare";

assert.equal(
  looseCompare(
    {
      a: {
        b: "d",
        c: [],
        e: "f",
        g: "h",
      },
    },
    {
      a: {
        b: "d",
        c: [],
      },
    }
  ),
  true
);

§ Examples

• program example: More Examples
• program example: Empty Values

§ Purpose

To find out, does an object/array/string/nested-mix is a subset or equal to another input.

If this library will encounter two things that contain only empty things, it will report them as equal. Empty things are:

• strings that trim() to zero length
• arrays with zero or more empty strings (see previous item)
• plain objects whose all values of all keys are empty arrays, empty strings or empty plain objects

For example these two are deemed to be equal:

looseCompare(
  {
    a: "a",
    b: "\n \n\n",
  },
  {
    a: "a",
    b: "\t\t \t",
  }
);
// => true

Second input argument can be subset of first-one, notice b values are of a different type, yet both contain only empty space:

looseCompare(
  {
    a: "a",
    b: [[["\n \n\n"]]],
    c: "c",
  },
  {
    a: "a",
    b: { c: { d: "   \t\t \t" } },
  }
);
// => true

§ API

looseCompare(bigObj, smallObj)

In other words, it's a function which takes two input arguments, both obligatory.

It returns a boolean or undefined.

• If everything from smallObj matches everything within bigObj, this library returns true.
• Otherwise, if there's a mismatch, returns false.
• For all other cases where inputs are missing/undefined, returns undefined.
• If both smallObj and bigObj contain the same key and their values contain only empty space (differing or not), they will be considered equal.

§ Difference from ast-compare

ast-compare of ours does everything that this program does and more.

§ Differences from _.isMatch

"Partial comparisons will match empty array and empty object source values against any array or object value, respectively." — Lodash documentation 

_.isMatch  positively matches empty arrays to everything. This is bad when you are comparing parsed HTML/CSS trees. This library doesn't do this. In this library, empty array will not be reported as equal to non-empty array, although if both arguments contain something which is empty space, they will be considered equal.

If you want an AST comparison library with a stricter ways towards the empty space equation, check ast-compare.

§ Changelog

See it in the monorepo , on Sourcehut.

§ Licence

MIT 

Copyright © 2010–2020 Roy Revelt and other contributors