@extra-array/is-unique/index.js

Checks if there are no duplicate values.

'use strict';
function id(v) {
    return v;
}
function cmp(a, b) {
    return a < b ? -1 : (a > b ? 1 : 0);
}
function isUniqueMap(x, fm = null) {
    var fm = fm || id;
    var s = new Set(), i = -1;
    for (var v of x) {
        var v1 = fm(v, ++i, x);
        if (s.has(v1))
            return false;
        s.add(v1);
    }
    return true;
}
function isUniqueDual(x, fc = null, fm = null) {
    var fc = fc || cmp, fm = fm || id;
    var x1 = [...x].map(fm);
    for (var u1 of x1) {
        for (var v1 of x1)
            if (fc(u1, v1) === 0)
                return false;
    }
    return true;
}
function isUnique(x, fc = null, fm = null) {
    if (fc)
        return isUniqueDual(x, fc, fm);
    else
        return isUniqueMap(x, fm);
}
module.exports = isUnique;