A question about defining parentheses in js, please help me_html/css_WEB-ITnose

This is written in js: var a=("1","2","5",6);
alert(a); The pop-up is 6
I don’t know what the grammatical meaning of this is What? I checked a lot of information and found no similar usage. Seek advice from experts! Thanks! ! !

Reply to discussion (solution)

(,) operator can perform multiple expression operations in one statement and return the value of the last expression to variable a

Oh, I understand, thank you, Brother Mengzi! ! !

The following is the array and the front is the variable value. It must be 6

You can traverse each(function(){
});