Problem in indexOf in javascript

I want to find out if a variable value contains in second string. My code is

if (ext.indexOf(FileUploadval.substring(FileUploadval.lastIndexOf('.') + 1)) == -1) {
}

where ext have va开发者_StackOverflow社区lue pdf,doc,dox,xls,xlsx,ppt,pptx and when i try xls or xlsx file it goes in if condition but when i try doc or pdf it doesnot go in if condition. what can be the problem?

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Maybe case sensitive

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Check the case of the file extensions (UPPER vs lower vs miXeD)

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Try the following:

if (ext.indexOf(FileUploadval.toLowerCase().substring(FileUploadval.toLowerCase().lastIndexOf('.') + 1)) == -1) {
}