The buf.indexof()
function takes a value and returns the index of where that value first occured in the buffer.
The buf.indexOf()
function accepts three parameters:
value
: The buf.indexOf()
function returns the first occurrence of value
in the buffer (buf
). value
can be of type string
, buffer
,integer
, and Uint8Array
.byteoffset
: Indicates where to begin the search in the buffer (buf
), and is set to 0 by default. If byteoffset
is negative, it is set to the end of the buffer (buf
). byteoffset
is of type integer
.encoding
: Determines the binary representation of the value
if it is of type string
. encoding
is set to utf-8
by default.The buf.indexOf()
function returns an integer indicating the index at which the value
lies in the buffer (buf
), and returns -1 if the value
does not exist in buf
.
Note: The program will throw a
TypeError
ifvalue
is not a string, buffer, or integer.
The following code demonstrates how to use the Buffer.indexOf()
function in Node.js.
// create a buffervar buf = Buffer.from("Educative.io")//call the indexOf() functionconsole.log(buf.indexOf('e'))// set the offset to the 4th byteconsole.log(buf.indexOf('i',4))//input the ascii value of cconsole.log(buf.indexOf(99))//input an out of range number. 97 is the ascii of a.console.log(buf.indexOf(97+256))//input the value as a bufferconsole.log(buf.indexOf(Buffer.from('tive.io')))
The above program applies the buf.indexOf()
function on values of type string, buffer, and integer.
indexOf()
function on a buffer created with a string and obtains the indexes of the string’s characters in the buffer.indexOf()
function and returns the index from where the other buffer starts.Note: If
value
is a number outside of the range 0-255, the number is converted into a valid byte integer. Ifbyteoffset
is not a valid byte, it is converted into a valid byte. The entire buffer is searched ifbyteoffset
is converted to 0 or NaN.
Free Resources