javascript indexOf()

[shooter2749]

so I have to show every month with the letter R in it (month is "mois" in french, all the month name are in french sorry)

I think I got it right but for some reason it displays all the months idk why 

var mois =['Janvier','Février','Mars','Avril','Mai','Juin','Juillet',
            'Aout','Septembre','Octobre','Novembre','Décembre'];
            for(var i =0;i<mois.length;i++)
            {
                
                if(mois[i].indexOf('r'))
                {
                    document.writeln(mois[i])
                }
            }

 

[79wjd]

11 minutes ago, shooter2749 said:

so I have to show every month with the letter R in it (month is "mois" in french, all the month name are in french sorry)

I think I got it right but for some reason it displays all the months idk why 

var mois =['Janvier','Février','Mars','Avril','Mai','Juin','Juillet',
            'Aout','Septembre','Octobre','Novembre','Décembre'];
            for(var i =0;i<mois.length;i++)
            {
                
                if(mois[i].indexOf('r'))
                {
                    document.writeln(mois[i])
                }
            }

 

The if branch will always be taken. You need to make it:

if (mois[i].indexOf('r') >= 0)

[elpiop]

You need to check if mois.indexOf('r') !== -1. indexOf returns -1 if it cannot find the given element, and -1 evaluates to true, which is why all months are being displayed

[PAEz]

If your using a modern browser you could also have used 'includes'....

 

 if(mois[i].includes('r'))

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes

[vorticalbox]

2 hours ago, PAEz said:

If your using a modern browser you could also have used 'includes'....

 

 if(mois[i].includes('r'))

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes

This better as you're only after if an item is there not where the item is.