String.prototype.indexOf

Returns the index of the first occurrence of a substring in the string.

Syntax

indexOf(substring, startIndex?)

Parameters

• substring

  The substring to search for in the string

• startIndex optional

  The index at which to begin searching. If omitted, search starts at the beginning of the string.

Return value

The index of the first occurrence of the specified substring, or -1 if not found.

Examples

"banana".indexOf("na")

2

"banana".indexOf("no")

-1