dom event error

Hi.
I’m getting this error message from CF7:
var wpcf7Elm = document.querySelector( ‘.wpcf7’ ); wpcf7Elm.addEventListener( ‘wpcf7submit’, function( event ) { console.log(‘form-sent’); }, false );

I have read the documentation and didn’t understand what went wrong.
how can i solve this error message.

Thank you very much.

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