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srikumarks/js_const_var_speed.js

Created December 4, 2011 23:26
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  1. srikumarks created this gist Dec 4, 2011.
    100 changes: 100 additions & 0 deletions js_const_var_speed.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,100 @@

    function timeit(f, N, S) {
    var start, timeTaken;
    var stats = {min: 1e50, max: 0, N: 0, sum: 0, sqsum: 0};
    var i;
    for (i = 0; i < S; ++i) {
    start = Date.now();
    f(N);
    timeTaken = Date.now() - start;

    stats.min = Math.min(timeTaken, stats.min);
    stats.max = Math.max(timeTaken, stats.max);
    stats.sum += timeTaken;
    stats.sqsum += timeTaken * timeTaken;
    stats.N++
    }

    var mean = stats.sum / stats.N;
    var sqmean = stats.sqsum / stats.N;

    return {min: stats.min, max: stats.max, mean: mean, spread: Math.sqrt(sqmean - mean * mean)};
    }

    var variable1 = 10;
    var variable2 = 10;
    var variable3 = 10;
    var variable4 = 10;
    var variable5 = 10;
    var variable6 = 10;
    var variable7 = 10;
    var variable8 = 10;
    var variable9 = 10;
    var variable10 = 10;

    function varAccess(N) {
    var i, sum;
    for (i = 0; i < N; ++i) {
    sum += variable1;
    sum += variable2;
    sum += variable3;
    sum += variable4;
    sum += variable5;
    sum += variable6;
    sum += variable7;
    sum += variable8;
    sum += variable9;
    sum += variable10;
    }
    return sum;
    }

    const constant1 = 10;
    const constant2 = 10;
    const constant3 = 10;
    const constant4 = 10;
    const constant5 = 10;
    const constant6 = 10;
    const constant7 = 10;
    const constant8 = 10;
    const constant9 = 10;
    const constant10 = 10;

    function constAccess(N) {
    var i, sum;
    for (i = 0; i < N; ++i) {
    sum += constant1;
    sum += constant2;
    sum += constant3;
    sum += constant4;
    sum += constant5;
    sum += constant6;
    sum += constant7;
    sum += constant8;
    sum += constant9;
    sum += constant10;
    }
    return sum;
    }


    function control(N) {
    var i, sum;
    for (i = 0; i < N; ++i) {
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    sum += 10;
    }
    return sum;
    }

    console.log("ctl = " + JSON.stringify(timeit(control, 10000000, 50)));
    console.log("con = " + JSON.stringify(timeit(constAccess, 10000000, 50)));
    console.log("var = " + JSON.stringify(timeit(varAccess, 10000000, 50)));