How to compare dates in javascript with two different format?

问题

function mainFunc() {
    dueDate = "30/12/2014";
    var firstReminderDate = dueDate;
    var today = new Date();
    var firstDate = convertToDate(firstReminderDate);
    if (today > firstDate) {
        //send reminder to A
    } else {
        // send reminder to B
    }
}

function convertToDate(dateString) {
    var dateData = dateString.split("/");
    var date = new Date(new Date().setFullYear(dateData[0], dateData[1] - 1, dateData[2]));
    return new Date(date);
}

I need to compare two dates not the time, and how to remove the time part and just compare the dates? The convertToDate() is returning the "Thu Jan 01 05:30:00 GMT+05:30 1970" everytime?

回答1:

You can simplify your code. To get a date from dd/mm/yyyy, simply splitting on /, reversing the result and joining it on '/' gives you yyyy/mm/dd, which is valid input for a new Date to compare to some other Date. See snippet

var report = document.querySelector('#result');
report.innerHTML += '30/12/2014 => '+ mainFunc('30/12/2014');
report.innerHTML += '<br>01/12/2014 => '+ mainFunc('01/01/2014');

function mainFunc(due) {
    due = due ? convertToDate(due) : new Date;
    return new Date > due 
           ? due +' passed: <b>send reminder to A</b>'
           : due +' not passed: <b>send reminder to B</b>';
}

function convertToDate(dateString) {
    return new Date(dateString.split("/").reverse().join('/'));
}

<div id="result"></div>

回答2:

Just return it in milliseconds format

function convertToDate(dateString) {
    var dateData = dateString.split("/");
    return +new Date(new Date().setFullYear(dateData[0], dateData[1] - 1, dateData[2]));
}

And also change var today = new Date(); to var today = +new Date();. Now it should work. + here converts Date object to milliseconds.

回答3:

The best way to compare two date is to instanciate them with same object, here you must use Date object.

function mainFunc(){
    var firstDate = new Date( dueDate = "30/12/2014" );
    today = new Date(); 

    if( today > firstDate ){
     //...
    }
    else{
     //...
    }
}

回答4:

I will recomend momentjs lib to parse, validate, manipulate, and display dates in JavaScript.

var firstDate = moment("30/12/2014", "DD/MM/YYYY")
var today = moment();

// Format to Unix Timestamp to compare
if(today.format('X') > firstDate.format('X')){

  //send reminder to A
}else{

  // send reminder to B
}

Here is the link http://momentjs.com/

来源：https://stackoverflow.com/questions/27521203/how-to-compare-dates-in-javascript-with-two-different-format

标签

javascript

date

data-conversion