javascript - DOM gets the difference between elements with or without quotes when creating and inserting

Question

{code...}

三叔 · Answer

With quotes it is a string

var h1 = document.createElement('h1');
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    A                            B

Unquoted are variables:

document.body.appendChild(h1);
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                          A

See the document: document.getElementById

element = document.getElementById(id);

element is an Element object. If the element with the specific ID does not exist in the current document, return null.

id is a case-sensitive string, which represents the unique ID of the element you are looking for.

h1 is an Element object, 'h1' is a string.

滿天的星座 · Answer

It depends on the situation that you are a beginner, so don’t make some confusing variable names. This is your own responsibility. For example:

var _h1 = document.createElement('h1');

某草草 · Answer

When creating a tag, + is used. When inserting, it is equivalent to h1 being a variable. It is not + at this time

伊谢尔伦 · Answer

Without the representative symbol, it is a variable; with the representative symbol, it is a string

曾经蜡笔没有小新 · Answer

var h1 = document.createElement('h1');

h1 in this line is a variable, representing a newly created element. It will be easier to understand if you change the variable name.

var node = document.createElement('h1');
document.body.insertBefore(node,btn);