Built-in JMeter Functions

JMeter allows you to conduct performance tests on your application by using any type of request. During these tests, we sometimes need to create new data, timestamps, or maybe manipulate a response.

For these purposes, JMeter provides built-in functions easily adaptable to your tests. Let’s explore the ones that you might need during a test.

Random Strings

There are a few different ways to create a random string in JMeter.

Examples:

 ${__RandomString(5)} will create a random string, It can be readable or not.

 ${__RandomString(5,ABCD123)} will create a random string containing only the alphanumeric values that you provide.

 ${__RandomString(5,,var)} will create a random string, then assign the value to a variable. You will be able to use that variable in another script by using the ${var} expression. The second parameter for the RandomString function is optional.

Random Numbers

There are a few different ways to create a random string in JMeter.

Examples:

 ${__Random(5)} will create a random number with a defined length.

 ${__Random(5,var)} will create a random number with a defined length, then assign the value to a variable. So you will be able to use that variable in another script by using ${var} expression.

UUID

A universally unique identifier (UUID) is a 128-bit number used to identify information in computer systems. In order to create one in JMeter, you should use the __UUID() functionality. UUID is almost unique as its length and random

 ${UUID()} will give you a value like 0c7dba7e-7587-46d0-88f2-dfe577b88432

Split Strings

If you need to split a String with a delimiter, you can use the ${SPLIT()} functionality.

Just create a BeanShell Processor where you want the split operation to happen. Then add  ${__split(${param},splitParam,|)} in the BeanShell script field.

1st Parameter: Parameter that you want to split.

2nd Parameter: After the split, split values will be assigned to this variable. You need to define an index when using it.

3rd Parameter: Delimiter that you have in the String.

Example:

Param = canberk|akduygu|loadium
splitParam_1 = canberk
splitParam_2 = akduygu
splitParam_3 = loadium

Time

You can use the Time functionality to get the current time with different formats. You can specify a date/time format to format time values.

 ${__time(dd/MM/yyyy,)} will get you 02/12/2018

 ${__time(dd-mmm-yyyy hh:mm,)} will get you 02-12-2018 12:22

 ${__time()} will get you a timestamp like 1598723200239

There are many other functions that you would use with JMeter but in case those functions are not sufficient for you, JavaScript is here to help you.

JavaScript

You can use the __javaScript() function to pass any JavaScript code as a parameter, and do more extreme things, as well.

Examples:

Create a number between 0-10:

 ${__javaScript(Math.floor(Math.random() * 10))} 

Compare a variable to a hardcoded string then storing true/false result to a variable:

 ${__javaScript(“${username}”==”canberk”,found)} 

Happy testing!