javascript时间格式转换（今天，昨天，前天）

function transDate() {
        var $time =document.getElementById("share-time");
        var date = $time.innerHTML.trim();
        var tt = new Date(parseInt(date));
        var days = parseInt((new Date().getTime() - date) / 86400000);
        var today = new Date().getDate();
        var year = tt.getFullYear();
        var mouth = tt.getMonth() + 1;
        var day = tt.getDate();
        var time = tt.getHours() < 10 ? "0" + tt.getHours() : tt.getHours();
        var min = tt.getMinutes() < 10 ? "0" + tt.getMinutes() : tt.getMinutes();
        var result, offset;
　　　　　　　offset = Math.abs(today - day);
　　　　if (days < 4&&offset<4) {
　　　　　　　if (offset === 0) {

                result = "今天" + time + ":" + min;
            } else if (offset === 1) {
                result = "昨天" + time + ":" + min;
            } else if (offset === 2) {
                result = "前天" + time + ":" + min;
            }
        } else {
            result = year + "-" + mouth + "-" + day + " " + time + ":" + min;
        }
        $time.innerHTML = result;
    }
    transDate();