How to pass functions to Selenium's JavaScript executor?

Question

Let's say I have a JS function like that:

function someFunction(callback) {
   callback()
}

and I want to call it from Selenium. for normal arguments (e.g. strings, arrays, integers, maps, HTML Elements) I can do:

driver.executeScript("someFunction(arguments[0])", "() => console.log('hi')")

and Selenium automatically converts/escapes the arguments. but if an argument is a function, then it's passed as a string. the call above becomes:

someFunction("() => console.log('hi')")

but it should have been:

someFunction(() => console.log('hi'))

is there a way to tell Selenium that the passed argument is a function?

you'd just pass the function and the call to the function as a string... it's a script so it's not interpreted yet, so you should be fine. I.e. you send "someFunction(() => console.log('hi')); " along with the function you are calling: "function someFunction(callback) { callback() }" ... as part of the same string... no need to pass as argument. — browsermator
– browsermator, Commented Nov 8, 2022 at 23:11
that makes sense for static strings. but if you want to make something generic, it's a bit more painful and you lose the benefits of Selenium arguments conversions (e.g. in maps and lists). look at the hack I had to do: github.com/lsoares/selenium-testing-library/blob/main/lib/src/… — Luís Soares
– Luís Soares, Commented Nov 9, 2022 at 10:47

pguardiario · Accepted Answer · 2022-11-09 00:48:42Z

1

with eval:

driver.executeScript("""
  var fn = eval(arguments[0])
  fn()
""", "() => console.log('hi')")

Note: I don't know how to escape quotes in java, this is python-style

answered Nov 9, 2022 at 0:48

pguardiario

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2 Comments

that's interesting but it is only for raw status cases. if you have a map of options and one option can be a function it's not so easy. this is a hack I had to do github.com/lsoares/selenium-testing-library/blob/main/lib/src/…

Not really, eval works for other types. eval("2") => number, eval("'2'") => string