method-memoize

Method decorator to memoize class instance methods. Like the normal memoize but this one doesn't share a cache between instances. Each instance gets its own cache.

https://www.npmjs.com/package/method-memoize

npm install --save method-memoize

Usage

var memoize = require('method-memoize');

function Multiply(n) {
  this.n = n;
}

Multiply.prototype.by = memoize(function(x) {
  return this.n * (x || 1);
});

var five = new Multiply(5);
var seven = new Multiply(7);
// Cache misses
equal(five.by(5), 25);
equal(seven.by(3), 21);
// These are already cached
equal(five.by(5), 25);
equal(seven.by(3), 21);
// This one is not, because it is a different instance
var five2 = new Multiply(5);
equal(five2.by(5), 25);

function equal(a, b) {
  console.log(a+'==='+b, a === b);
}

Why?

When you want a normal memoize, but the functions depend on the guts of this, it is sometimes useful to memoize methods based on instance. Obviously if the guts of the object keep on mutating this memoization won't be useful and will give incorrect results.