how to combine two different properties to single property in javascript code example

Example 1: merge objects js

/* For the case in question, you would do: */
Object.assign(obj1, obj2);

/** There's no limit to the number of objects you can merge.
 *  All objects get merged into the first object. 
 *  Only the object in the first argument is mutated and returned.
 *  Later properties overwrite earlier properties with the same name. */
const allRules = Object.assign({}, obj1, obj2, obj3, etc);

Example 2: javascript combine objects

const obj1 = {'a': 1, 'b': 2};
const obj2 = {'c': 3};
const obj3 = {'d': 4};

const objCombined = {...obj1, ...obj2, ...obj3};