User Login Programmatically in WordPress

Custom JS code enqueued in active theme functions.php

  var userdata = { 

                  'action'   : 'signin_member', 

                  'username' : jQuery('#user_name').val(),

                  'password' : jQuery('#password').val()

                 };

  jQuery.ajax({

      url    : yup.ajaxurl,

      type   : 'POST',

      data   : userdata,

          beforeSend: function() {

          },

          success: function(response) {      

              responseobj = jQuery.parseJSON(response);

              if (responseobj['flag'] == 'success') {

                  jQuery('#message').text(responseobj['message']);

              }

              if( '' != responseobj['redirecturl'] ){

                  window.location.href = responseobj['redirecturl'];

              }

          }

  });

});

Code to be added on active themes functions.php

add_action('wp_ajax_signin_member','signin_member_callback');

add_action('wp_ajax_nopriv_signin_member','signin_member_callback');

function signin_member_callback(){

	if(trim($_POST["username"] == '' )  || trim($_POST["password"] == '' )  ){

		echo json_encode(array('flag'=>'failure','message'=> 'Please enter both username and password.' ));

	}else

	{

		$user_login     = esc_attr($_POST["username"]);

		$user_password  = esc_attr($_POST["password"]);

		$creds = array();

		$creds['user_login']    = $user_login;

		$creds['user_password'] = $user_password;

		$creds['remember']      = true;

		$user = wp_signon( $creds, false );

		$userID = $user->ID;

		wp_set_current_user( $userID, $user_login );

		wp_set_auth_cookie( $userID, true, false );

		do_action( 'wp_login', $user_login );

	    if (is_wp_error($user) ) {

	 		echo json_encode(array('flag'=>'failure','message'=> 'Invalid username or password.' ));

	       	die();

	    } else {

	        wp_set_auth_cookie( $user->ID, 0, 0);

	        echo json_encode(array('flag' => 'success','message' => 'Logged in sucessfully','redirecturl' => get_field('community_page','option') ));

	        die();

	  	}

	}

}