JSFiddle - React, Tailwind, and code Playground

by Marlin

JavaScript

function Set() {          // This is the constructor
    this.values = {};     // The properties of this object hold the set
    this.n = 0;           // How many values are in the set
    this.add.apply(this, arguments);  // All arguments are values to add
}

// Add each of the arguments to the set.
Set.prototype.add = function() {
    for(var i = 0; i < arguments.length; i++) {  // For each argument
        var val = arguments[i];                  // The value to add to the set
        var str = Set._v2s(val);                 // Transform it to a string
        if (!this.values.hasOwnProperty(str)) {  // If not already in the set
            this.values[str] = val;              // Map string to value
            this.n++;                            // Increase set size
        }
    }
    return this;                                 // Support chained method calls
};

// Remove each of the arguments from the set.
Set.prototype.remove = function() {
    for(var i = 0; i < arguments.length; i++) {  // For each argument
        var str = Set._v2s(arguments[i]);        // Map to a string
        if (this.values.hasOwnProperty(str)) {   // If it is in the set
            delete this.values[str];             // Delete it
            this.n--;                            // Decrease set size
        }
    }
    return this;                                 // For method chaining
};

// Return true if the set contains value; false otherwise.
Set.prototype.contains = function(value) {
    return this.values.hasOwnProperty(Set._v2s(value));
};

// Return the size of the set.
Set.prototype.size = function() { return this.n; };

// Call function f on the specified context for each element of the set.
Set.prototype.foreach = function(f, context) {
    for(var s in this.values)                 // For each string in the set
        if (this.values.hasOwnProperty(s))    // Ignore inherited properties
            f.call(context, this.values[s]);  // Call f on the value
};

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