Javascript checking if a variable is between 2 values + else

Question

I need help with this simple issue. Whenever I activate the code below, I always get the result from else, no matter my input. I want to check if the day is between 1 and 30 inclusive, and if it is activate whatever is inside the if function. If it's not between 1 and 30, I want to run the else function and display the error message.

var day;
    function changePage(){
        if(day < 30 && day > 1){
           day = document.getElementById("inputBox").value;
           console.log(day);
           window.location.href = "day-" + day + ".html";}
        else{
           alert("Invalid entry, must be between 1 and 30");}}

where do you assign day value?

Kukic Vladimir
– Kukic Vladimir

2017-07-11 10:45:32 +00:00
Commented Jul 11, 2017 at 10:45 — Kukic Vladimir
– Kukic Vladimir, Commented Jul 11, 2017 at 10:45
day === undefined so it's not between 1 and 30.

Liam
– Liam

2017-07-11 10:47:18 +00:00
Commented Jul 11, 2017 at 10:47 — Liam
– Liam, Commented Jul 11, 2017 at 10:47

Ian · Accepted Answer · 2017-07-11 10:47:00Z

2

Your day isn't set until you hit the loop. You need to define day either outside or within the function but before the loop

function changePage() {
    var day = document.getElementById("inputBox").value;
    if (day < 30 && day > 1) {
        console.log(day);
        window.location.href = "day-" + day + ".html";
    } else {
        alert("Invalid entry, must be between 1 and 30");
    }
}

answered Jul 11, 2017 at 10:47

Ian

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2 Comments

Mishapopkin Over a year ago

DUUUUUH! Thank you.

Ian Over a year ago

Not a problem @Mishapopkin we all make those mistakes ^_^

cнŝdk · Accepted Answer · 2017-07-11 10:54:48Z

0

I always get the result from else

Yes it's logical because day in your code is undefined so the following if statement if(day < 30 && day > 1) will be always false so the else part will be always reached.

In your deaclartion initialize the day variable, like this:

var day = document.getElementById("inputBox").value;

answered Jul 11, 2017 at 10:54

cнŝdk

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Comments

Mishapopkin · Accepted Answer · 2017-07-11 11:00:50Z

0

Yes I understand, I defined day inside my function. I changed it to outside the if else function and it worked. Thank you everyone.

answered Jul 11, 2017 at 11:00

Mishapopkin

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