test.js

var assert = require('assert');
var throttle = require('./');

describe('throttle', function() {
  it('executes right away', function() {
    var passed = false;
    var throttled = throttle(function() {
      passed = true;
    }, 10);
    throttled();
    assert(passed);
  });

  it("won't execute more than once within the threshold", function(done) {
    var called = 0;
    var throttled = throttle(function() {
      called++;
    }, 10);
    throttled();
    throttled();
    throttled();
    setTimeout(function() {
      assert.equal(called, 1);
      done();
    }, 5);
  });

  it("will execute at least once more to make up for swallowed calls", function(done) {
    var called = 0;
    var throttled = throttle(function() {
      called++;
    }, 10);
    throttled();
    throttled();
    setTimeout(function() {
      assert.equal(called, 2);
      done();
    }, 15);
  });

  it('will execute every threshold ms', function(done) {
    var called = 0;
    var throttled = throttle(function() {
      called++;
    }, 10);
    var interval = setInterval(throttled, 2);
    setTimeout(function() {
      clearInterval(interval);
      assert.equal(called, 6);
      // it'll be called again in another 5 ms, but last test took care of that

      done();
    }, 55);

  });

  it('gets called with context', function() {
    var ctx;
    var throttled = throttle(function() {
      ctx = this;
    }, 10);
    throttled.call(22);
    assert.equal(ctx, 22);
  });

  it('gets called with arguments', function() {
    var args;
    var throttled = throttle(function() {
      args = [].slice.call(arguments);
    }, 10);
    throttled(22, 33, 44);
    assert.deepEqual(args, [22, 33, 44]);
  });

  it('gets called with the later arguments', function(done) {
    var args;
    var throttled = throttle(function() {
      args = [].slice.call(arguments);
    }, 10);
    throttled(11, 22, 33);
    throttled(22, 33, 44);
    throttled(33, 44, 55);
    setTimeout(function() {
      assert.deepEqual(args, [33, 44, 55]);
      done();
    }, 15)
  });


});