Merging two or more maps together means that you want one map with key-value pairs from every map. The challenge comes where two of the maps have the same key.
When merging maps, there's always the chance that keys will conflict. The question is, which value gets used? Let's illustrate this idea by merging two simple lists together:
const myMap1 = Map.of(
'one', 1, 'two', 2, 'three', 3
);
const myMap2 = Map.of(
'two', 22, 'three', 33, 'four', 4
);
const myMergedMap = myMap1.merge(myMap2);
console.log('myMap1', myMap1.toJS());
// -> myMap1 { one: 1, two: 2, three: 3 }
console.log('myMap2', myMap2.toJS());
// -> myMap2 { two: 22, three: 33, four: 4 }
console.log('myMergedMap', myMergedMap.toJS());
// -> myMergedMap { one: 1, two: 22, three: 33, four: 4 }As you can see, myMergedMap contains every key from myMap1 and myMap2. There are two conflicting keys—two and three. By default, the merge() method will just override existing values. If you want...