function log() {    var i = 0,        str = ‘‘,        args = [].slice.call(arguments);    j++;    if (isRepeat(args)) {        k++;        return;    }    while(i < args.length) {        str += chars[args[i]];        i++;    }    console.log(str);}function count(obj) {    var i = 0;    for (var p in obj) {        if (obj.hasOwnProperty(p)) {            i++;        }    }    return i;}function isRepeat(arr) {    var i = 0,        obj = {};    while(i < arr.length) {        obj[typeof arr[i] + arr[i]] = 1;        if (count(obj) === i) {            return true;        }        i++;    }    return false;}function loop(min, max, fn, count) {    var i, args;    i = min;    count++;    args = [].slice.call(arguments, 0);    while(i < max) {        var iargs = args.slice(0);        iargs.push(i);        fn.apply(window, iargs.slice(4));        if (count < max - min) {            arguments.callee.apply(window, iargs);        }        i++;    }}var chars = [‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘];var j = 0, k = 0;loop(0, chars.length, log, 0);console.log(‘共执行‘, j, ‘次, 不允许单字符重用有‘, j - k, ‘次, 允许单字符重用有‘, k, ‘次‘);