While joining two arrays, postfix non-unique values with (number) incrementally of joining array-CodePudding

I have two arrays:

Array 1 : [{name: "Darin", id: "123"}, {name: "Mads", id: "345"}, {name: "Kenneth", id: "543"}, {name: "June", id: "567"}, {name: "June (1)", id: "789"}]
Array 2 : [{name: "Darin", id: "910"}, {name: "June", id: "911"}, {name: "Simon", id: "912"}, {name: "Justin", id: "913"}]

The output that I want is as follows:

[{name: "Darin", id: "123"}, {name: "Mads", id: "345"}, {name: "Kenneth", id: "543"}, {name: "June", id: "567"}, {name: "June (1)", id: "789"}, {name: "Darin (1)", id: "910"}, {name: "June (2)", id: "911"}, {name: "Simon", id: "912"}, {name: "Justin", id: "913"}]

As you can see, I have the following rules:

Array 2 should be the only array in which I postfix (...num)
Eventual duplicates should be postfixed with (number) where number increments until the value becomes unique in the joined array

I'm unsure where to start in order to achieve the above. I can see this solved with a bunch of loops and a recusive function - But really, that's inefficient.

I can see that Javascript ES6 offers some "newer" methods that could pose handy in this scenario - In particular map and set.

Consequently, my question seeks to understand how I can achieve the above, while paying attention to time complexity.

CodePudding user response：

Using Array.map, and a counter object to keep track of the number of times each name already occurred:

var input1 = [{name: "Darin", id: "123"}, {name: "Mads", id: "345"}, {name: "Kenneth", id: "543"}, {name: "June", id: "567"}, {name: "June (1)", id: "789"}];

var input2 = [{name: "Darin", id: "910"}, {name: "June", id: "911"}, {name: "Simon", id: "912"}, {name: "Justin", id: "913"}];

var counter = {};
var combined = input1.concat(input2).map(function(e) {
  var strippedName = e.name.replace(/ \([0-9] \)/, '');
  counter[strippedName] = counter[strippedName] == undefined ? 0 : counter[strippedName]   1;
  e.name = strippedName   (counter[strippedName] ? ' (' counter[strippedName] ')' : '');
  return e;
});
console.log(combined);

CodePudding user response：

You could count the names by separating the strings.

const
    array1 = ["Darin", "Mads", "Kenneth", "June", "June (1)"],
    array2 = ["Darin", "June", "Simon", "Justin"],
    counts = {},
    result = [array1, array2].reduce((r, a) => {
        a.forEach(v => {
            const [, name, , count = 0] = v.match(/^(\w*)(\s\((\d )\))?$/);
            if (name in counts && count === 0)   counts[name];
            else counts[name] = count;
            r.push(counts[name] ? `${name} (${counts[name]})` : name);
        });
        return r;
    }, []);

console.log(result);

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