javascript indexOf always returning -1

Question

making (lame) game, and i want to check if selected square contains a monster, however my indexOf keeps returning -1. relevant code below.

intialization:

var monsters = [];

var monsterPositions = [2,8,13,15,22];

var player = { "currentPosition": 0 };

for ( var i in monsterPositions ) {
    monsters[i] = new createMonster("monster",monsterPositions[i],1); }

function createMonster(name,startingPoint,level) {
    this.currentPosition = startingPoint; }

function triggered with <td> onclick:

function processClick(trigger){
    console.log( trigger.id + " " + monsterPositions );
    if ( monsterPositions.indexOf(trigger.id) >= 0 ){
        if ( !fight( findMonster( parseInt( trigger.id ) ) ) ){
            return;
        }
    }
    if ( gameOn ) move( parseInt( trigger.id ) );
}

the page always goes straight to move(), even when it is a monster spot, here is console.log() results:

1 2,8,13,15,22 adventure.js (line 79)
2 2,8,13,15,22 adventure.js (line 79)
7 2,8,13,15,22 adventure.js (line 79)
8 2,8,13,15,22 adventure.js (line 79)
13 2,8,13,15,22 adventure.js (line 79)
18 2,8,13,15,22 adventure.js (line 79)
23 2,8,13,15,22 adventure.js (line 79)
22 2,8,13,15,22 adventure.js (line 79)
21 2,8,13,15,22 adventure.js (line 79)
20 2,8,13,15,22 adventure.js (line 79)
15 2,8,13,15,22 adventure.js (line 79)

(link here if above code isnt enough), and im stumped help please.(of course why else would i be here)

Corey Ogburn · Accepted Answer · 2013-08-30 03:34:40Z

5

trigger.id is probably returning a string where your array is full of numbers.

This jsfiddle shows that in action as well as it working with a Number and how to convert your string IDs to numbers using parseInt().

answered Aug 30, 2013 at 3:34

Corey Ogburn

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4 Comments

Math chiller Over a year ago

oh wow i knew that just spaced, lol i had this before, (as you can see i use parseInt on the next line) thanks.

arb Over a year ago

Be sure to always pass 10 as the second argument of parseInt(trigger.id,10)

Math chiller Over a year ago

yeah whats up with that? i dont really get the whole "radix" thing.

arb Over a year ago

According to MDN "An integer that represents the radix of the above mentioned string. Always specify this parameter to eliminate reader confusion and to guarantee predictable behavior. Different implementations produce different results when a radix is not specified." If you do parseInt('08') on certain browsers, you won't get 8.

Milad Hosseinpanahi · Accepted Answer · 2013-08-30 03:38:59Z

1

try this

 if ( monsterPositions.indexOf(Number(trigger.id)) >== 0 )

edited Aug 30, 2013 at 3:38

answered Aug 30, 2013 at 3:31

Milad Hosseinpanahi

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5 Comments

Math chiller Over a year ago

ive never heard of number before i will check it up and try it, but parseInt is a known valid function, i dont see why it would work.

arb Over a year ago

It is bad practice to use Number

Math chiller Over a year ago

thanks anyway was a bit spaced didnt notice that i missed parseInt as you can see from my comment

godfrzero Over a year ago

@Zero21xxx Can you also add why it's bad practice? :D

arb Over a year ago

Well for one reason, it can easily be overridden. Anyone in any file can simply do Number = function() {return false} and BAM, now your code is broken. It is generally preferred to use literal notation if possible or any of the dozen other ways to convert a string to a number.

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