JavaScript-Why does this code commit to the past?

At first I was experimenting with this short code to start onsubmit= "return false" to write the direct return false so that the click button that prevents the form from being submitted does not have any reaction, and then I change to the form of a function to prevent form submission as if the following code looks Change it so people say you can stop the form submission but I'm not trying. Click the button is not a little reaction there will be a page refresh and address bar address will be more than one later? It's not the same as the previous direct return to false. The second paragraph of the code is also the case with onsubmit= "return check ()" Nothing to fill in the direct point commits can also be submitted to the database does not prevent the submission who knows my code where there is a problem why not prevent the submission?

Second paragraph

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At first I was experimenting with this short code to start onsubmit= "return false" to write the direct return false so that the click button that prevents the form from being submitted does not have any reaction, and then I change to the form of a function to prevent form submission as if the following code looks Change it so people say you can stop the form submission but I'm not trying. Click the button is not a little reaction there will be a page refresh and address bar address will be more than one later? It's not the same as the previous direct return to false. The second paragraph of the code is also the case with onsubmit= "return check ()" Nothing to fill in the direct point commits can also be submitted to the database does not prevent the submission who knows my code where there is a problem why not prevent the submission?

Second paragraph

function check(){         return false;        };

This sentence do not put in the window.onload inside, directly in the outer layer to try, I tried the feasible

Add a breakpoint to track it ~
Return function if code execution problems are handled by true

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