Editing Math.round vs hack This edit will create a new revision. Your details (optional) Name Email (won’t be displayed; might be used for Gravatar) URL Test case details Title * Published (uncheck if you want to fiddle around before making the page public) Description (in case you feel further explanation is needed)(Markdown syntax is allowed) Test of different ways of rounding numbers, results vary a lot according to browsers and JS engines are getting smarter each day, so it is usually a better approach to don't try to be smarter than the engines and use the native feature (in this case, `Math.round`) since there is a bigger chance of performance improvements in the future and especially because bitwise operations reduces code readability. Are you a spammer? (just answer the question) Preparation code Preparation code HTML (this will be inserted in the <body> of a valid HTML5 document in standards mode) (useful when testing DOM operations or including libraries) <script> var somenum = -500 + (Math.random() * 1000); var rounded; var round = Math.round; //cached </script> Include JavaScript libraries as follows: <script src="//cdn.ext/library.js"></script> Define setup for all tests (variables, functions, arrays or other objects that will be used in the tests) (runs before each clocked test loop, outside of the timed code region) (e.g. define local test variables, reset global variables, clear canvas, etc.) (see FAQ) Define teardown for all tests (runs after each clocked test loop, outside of the timed code region) (see FAQ) Code snippets to compare Test 1 Title Async (check if this is an asynchronous test) Code rounded = Math.round(somenum); Test 2 Title Async (check if this is an asynchronous test) Code rounded = ~~ (0.5 + somenum); Test 3 Title Async (check if this is an asynchronous test) Code rounded = (somenum + (somenum > 0 ? .5 : -.5)) |0; Test 4 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) | 0; Test 5 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) << 0; Test 6 Title Async (check if this is an asynchronous test) Code rounded = parseInt(0.5 + somenum) Test 7 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) & (0.5 + somenum) Test 8 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) >> 0; Test 9 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) >>> 0; Test 10 Title Async (check if this is an asynchronous test) Code rounded = (0.5 + somenum) ^ 0; Test 11 Title Async (check if this is an asynchronous test) Code rounded = round(somenum); Test 12 Title Async (check if this is an asynchronous test) Code rounded = Math.floor(somenum + 0.5); Test 13 Title Async (check if this is an asynchronous test) Code rounded = Math.ceil(somenum - 0.5);