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Check if a string includes the value of the string str.

'JavaScript'.includes('Script') //true
'JavaScript'.includes('script') //false
'JavaScript'.includes('JavaScript') //true
'JavaScript'.includes('aSc') //true
'JavaScript'.includes('C++') //false

includes() also accepts an optional second parameter, an integer which indicates the position where to start searching for:

'a nice string'.includes('nice') //true
'a nice string'.includes('nice', 3) //false
'a nice string'.includes('nice', 2) //true

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