JS1-7

• 按字面值创建数组

var arr = [1,2,3,4,5];

• 按构造方法创建数组

var arr = new Array(1,2,3,4);
//特殊的如果只写一个数字就是创建长度为该数字的一个数组
var arr2 = new Array(5);//创建一个长度为5的数组arr2

var a = '[a, b, c, d]';是一个string类型的变量
var b = [1, 2, 3, 4];是一个数组类型的变量

        var a = [1, 2, 3, 4, 5];
        for (var i = 0; i < a.length; i++) {
            a[i] *= 2;
        }
        console.log(a);

        var colors = ["Red", "Green", "White", "Black"];
        var case1 = "";
        for (var i = 0; i < colors.length; i++) {
            case1 = case1 + colors[i] + " ";
        }
        case1 = case1.slice(0, case1.length - 1);
        case2 = case1.replace(/\s+/g, "+");
        case3 = case1.replace(/\s+/g, ",");
        console.log(case1);
        console.log(case2);
        console.log(case3);

        var a = [5, 1, 8, 10, 4];

        function compare(val1, val2) {
            if (val1 < val2) {
                return -1;
            } else if (val1 > val2) {
                return 1;
            } else {
                return 0;
            }
        }
        a = a.sort(compare);
        a = a.reverse();
        console.log(a);

        var a = [3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3];
        var elements = [a[0]];
        var times = [1];
        for (var i = 1; i < a.length; i++) {
            var ele = a[i];
            for (var j = 0; j < elements.length; j++) {
                if (j == elements.length - 1 && ele !== elements[j]) {
                    elements[elements.length] = ele;
                    times[times.length] = 1;
                } else if (ele === elements[j]) {
                    times[j]++;
                    break;
                }
            }
        }
        var maxNum = 0;
        var maxIndex = 0;
        for (var i = 0; i < times.length; i++) {
            if (times[i] > maxNum) {
                maxNum = times[i];
                maxIndex = i;
            }
        }
        console.log(elements[maxIndex]);