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 
} 

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 
} 

• javascript
• if-statement
• time
• operators
• dayofweek

• 2 You use it wrongly, it will be: if ( dayOfWeek == 4 || dayOfWeek == 5 || dayOfWeek == 6 && hour >= 17 && hour < 19 ) { – Matteo Gaggiano Commented Jun 30, 2017 at 7:37
• 2 dayOfWeek == 4 || 5 || 6 this is invalid in javascript, you likely want to: [4,5,6].indexOf(dayOfWeek) > -1 && hour >= 17 && hour <19 -> note that this is an approach slightly different (using an array). – briosheje Commented Jun 30, 2017 at 7:37
• 1 Restate the condition for each condition! – Andrew Li Commented Jun 30, 2017 at 7:38
• @briosheje - What made you think of Array#indexOf ? #Amazing – Rayon Commented Jun 30, 2017 at 7:39
• 1 dayOfWeek == 4 == true or false. Whereas dayOfWeek == 4 || 5 will yield true or 5. Whereas dayOfWeek == 4 || 5 || 6 will still yield true or 5. It doesn't do what you want. – Stephen Quan Commented Jun 30, 2017 at 7:45

6 Answers 6

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 ) {

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
}

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/

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");
}

Your if condition should be:

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

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")
}