Dedupe Function Calls

Prevents a function being called multiple times with the same arguments + memoizes the return value;

Installation

npm install dedupe-function-calls

Works in node or the browser with browserify. Depends on underscore.

Usage

Can be used in two ways.

1. Typical use

   //Given a function which doubles a value:
   var double = function (value) {
       var doubled = value * 2;
       console.log('Doubled = ', doubled);
       return doubled;
   };
   
   //Without dedupe
   double(1); // logs 2, returns 2 
   double(1); // logs 2, returns 2
   double(1); // logs 2, returns 2
   double(2); // logs 4, returns 4
   double(1); // logs 1, returns 2
   
   //With dedupe
   var deduped = dedupe(double);
   deduped(1); // logs 2, returns 2 
   deduped(1); // no log, returns 2
   deduped(1); // no log, returns 2
   deduped(2); // logs 4, returns 4
   deduped(1); // logs 1, returns 2

   • Note that:
   • the function return value is memoized so subsequent calls still return values, they just don't execute the function body.
   • the original function can take any number of args (deduplication is based on all of the provided arguments).
   • It is different to memoization, in that it only dedupes sequential calls with the same value, not all calls

2. With a getter:

    ```javascript
    // Sometimes you want to use an objects value in a function, e.g:
    var myObject = {
        value: 2,
        double: function () {
            var doubled = this.value * 2;
            console.log('Doubled =', doubled)
            return doubled;
        }
    };
   
    //Deduping this is kind of a pain, as double isn't being passed any arguments, you could do this: 
   
    var myObject = {
        value: 2,
        _double: dedupe(function (value) {
            var doubled = value * 2;
            console.log('Doubled =', doubled)
            return doubled;
        }),
        double: function () {
            return this._double(this.value);
        }
    };
   
    myObject.double(1); //logs 2, returns 2
    myObject.double(1); //no log, returns 2
    myObject.double(1); //no log, returns 2
    myObject.value = 2;
    myObject.double(); //logs 4, returns 4
    myObject.double(); //no log, returns 4
   
    //But dedupe can actually take a getter function, so you can do:
    // (note that both the getter and the function will be called in the context of your object)
   
    var myObject = {
        value: 2,
        double: dedupe(
            function (value) {
                var doubled = value * 2;
                console.log('Doubled =', doubled);
                return doubled;
            },
            function () { return this.value; }
        )
    };
   
    ```