proxyequal/dist/es2015/weakMemoize.js

A proxy based usage tracking and comparison

export var weakMemoizeArray = function weakMemoizeArray(fn) {
  var cache = new WeakMap();
  return function (arg) {
    if (cache.has(arg)) {
      var old = cache.get(arg);

      if (old.length === arg.length) {
        return old.value;
      }
    }

    var ret = fn(arg);
    cache.set(arg, {
      value: ret,
      length: arg.length
    });
    return ret;
  };
};