javascript - getElementByTagName question -

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i know if want find group of elements, getelementsbytagname method , returns nodelist. if looking tag name "body" , why need add [0] after ("body") element? there 1 body tag in html document.

 var body = document.getelementsbytagname("body")[0];  body.classname = "unreadable";

why cant write code without index[0] this

 var body = document.getelementsbytagname("body");  body.classname = "unreadable";

if write code class unreadable not added body tag ...why?

because document.getelementsbytagname allways returns nodelist. if want find easier way retrieve body can use document.body


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