Javascript OR operator not working in if statement

问题

I'm trying to get this Javascript to do something if the day of the week matches any of the days listed in my statement, as well as restricting it to between 17:00 and 19:00 hours, but the OR operator is not working as I expected, I'm new to JS and I'm wondering if I'm misunderstanding the use of this operator. If I were to list a value for just one day of the week, instead of 3 like in my example, the code works as I'd hoped.

var d = new Date();
var dayOfWeek = d.getDay(); // 0 = Sunday
var hour = d.getHours();

if ( dayOfWeek == 4 || 5 || 6 && hour >= 17 && hour < 19 ){
    // do stuff
  } else {
    // do other stuff 
}

回答1:

In this case, you better use a range check, because you need only two comparisons against of three or more - and it is better maintanable, just to change a value, if necessary.

if (dayOfWeek >= 4 && dayOfWeek <= 6 && hour >= 17 && hour < 19) {

The right OR conditions needs parenthesis, because of the precedence of && over ||

if ((dayOfWeek == 4 || dayOfWeek == 5 || dayOfWeek == 6) && hour >= 17 && hour < 19 ) {

回答2:

Just for the sake of posting another possibility, if you ever will have a dynamic input you may want to use an array and use indexOf to check whether the day exists in the list:

var d = new Date();
var dayOfWeek = d.getDay(); // 0 = Sunday
var hour = d.getHours();

if ( [4,5,6].indexOf(dayOfWeek) > -1 && hour >= 17 && hour < 19 ){
    // do stuff
  } else {
    // do other stuff 
}

https://jsfiddle.net/hnzzfnot/1/

回答3:

You need to use dayOfWeek but you can also limit the amount of checks you need to do....

var d = new Date();
var dayOfWeek = d.getDay(); // 0 = Sunday
var hour = d.getHours();

if ( (dayOfWeek >= 4 && dayOfWeek <= 6) && (hour>=17 && hour < 19))
{
  // do stuff
}
else
{
  // doo other stuff
}

回答4:

var d = new Date();
var dayOfWeek = d.getDay(); // 0 = Sunday
var hour = d.getHours();

if ( (dayOfWeek == 4 || dayOfWeek == 5 || dayOfWeek == 6) && (hour >= 17 && hour < 19) ){
    // do stuff
    console.log("true");
  } else {
    // do other stuff 
    console.log("false");
}

回答5:

Your if condition should be:

if ( (dayOfWeek == 4 || dayOfWeek == 5 || dayOfWeek == 6) && hour >= 17 && hour < 19 ){
    // do stuff
  } else {
    // do other stuff 
}

回答6:

Correct it like this,

var d = new Date();
var dayOfWeek = d.getDay(); // 0 = Sunday
var hour = d.getHours();

if ( (dayOfWeek == 4 || 5 || 6) && (hour >= 17 && hour < 19) ){
    console.log("if")
  } else {
    console.log("else")
}

来源：https://stackoverflow.com/questions/44841084/javascript-or-operator-not-working-in-if-statement

标签

javascript

if-statement

time

operators

dayofweek