javascript中怎么实现打印一个杨辉三角形的前5行？

Question

javascript中怎么实现打印一个杨辉三角形的前5行？用循环嵌套的写法怎么写呢？

Answer 1

    function test() {
            var arr = new Array();
            for (var i = 0 ; i < 20 ; i++) {
                if (i == 0) {
                    arr.push(1);
                }
                else if (i == 1) {
                    arr = new Array();
                    arr.push(1);
                    arr.push(1);
                }
                else {
                    var arr2 = new Array();
                    arr2.push(1);
                    for (var j = 0; j < arr.length - 1; j++) {
                        arr2.push(arr[j] + arr[j + 1]);
                    }
                    arr2.push(1);
                    arr = new Array();
                    arr = arr2;
                }
                console.log(arr.join(" "));
            }
        }
        test();