I'm trying to do something like this

if (pathArray.toLowerCase().indexOf("blah") != -1{}

When debugging with console I get the error that "pathArray.toLowerCase is not a function". Why do I get that message?

I'm trying to do something like this

if (pathArray.toLowerCase().indexOf("blah") != -1{}

When debugging with console I get the error that "pathArray.toLowerCase is not a function". Why do I get that message?

• javascript

• Is pathArray an array? – Dave Zych Commented Oct 23, 2014 at 17:39
• pathArray is probably not a string. If it is an array, you probably want pathArray.some(function(v) { return v.toLowerCase() === 'blah';}); . – Felix Kling Commented Oct 23, 2014 at 17:39
• .toLowerCase() is a function in String.prototype. Most likely your pathArray is a different type of object. – Dave Commented Oct 23, 2014 at 17:39
• if pathArray is an array, toLowerCase() is a string method, you would need to traverse each element in array and convert it to lowercase. Also, you are missing a closing ) – juvian Commented Oct 23, 2014 at 17:39

6 Answers 6

toLowerCase is a method of the string. If you want to be able to find a string in array without knowing exact case you can add map step to the chain:

pathArray.map(function(s) { return s.toLowerCase(); }).indexOf('blah') !== -1

toLowerCase() is only for strings, but I have a feeling that your "pathArray" is, in fact, an array.

> 'hello'.toLowerCase()
'hello'
> ['hi', 'bye'].toLowerCase()
TypeError: undefined is not a function

Are you trying to check if "blah" exists in your array in any uppercase / lowercase form?

The toLowerCase method belongs to the String function prototype. So probably pathArray isn't a String. I have the feeling (for its name) that is an Array. In that case the following code could be useful for you:

pathArray.forEach(function(item, index){
    if(item.toLowerCase().indexOf("blah") != -1){
    }
});

The code proposed by dfsq could be useful too. It depends on what level you want to perform the indexOf function. In my case you will be performing search over each string in order to find the start index of the sub string "blah". In the dfsq's code you will be looking the array index which contains the the entire string "blah".

yes, it is an array so that makes sens now that it would not work. I'm trying to make indexOf. case insensitive.

No need for Array#indexOf():

if (pathArray.some(function(v) { return v.toLowerCase() === 'blah';}))

Array#some() returns true if for any element the callback returns true.

Your String is probably resides in index 0 of an Array.

Appling toLowerCase() on the 0 index should solve your issue:

pathArray[0].toLowerCase()

I was searching for a solution to the error "toLowerCase is not a function"

My issue was solved by adding .toString().toLowerCase() to the variable and that solved the issue