What is use for split() function in javascript ?

Answer 1

split() function is used to split a string into subsrings

See the example in w3schools
http://www.w3schools.com/jsref/jsref_split.asp

This is most often used when we have a string with comma separated items something like
"Tom,Dick,Harry"

Using this function we can split this string into a array of substrings [ "Tom" , "Dick" , "Harry"]