Differences between jQuery's methods for obtaining text nodes: text ()/val ()/html ()

In jquery, values such as val, text, and html can be obtained, or values are assigned by adding a parameter. What are the differences between them? The following is an example:
First, there are two methods in the html attribute: one with a parameter and the other without a parameter.
1. No parameter html (): obtains the html content of the First Matching Element. This function cannot be used in XML documents. But it can be used in XHTML documents and returns a String
Example:
Html page code: <div> <p> Hello </p> </div>
Jquery code: $ ("div" ).html ();
Result: Hello.
2. html (val): sets the html content of each matching element. This function cannot be used in XML documents. But it can be used in XHTML documents. Returns a jquery object.
Html page code: <div> </div>
Jquery code: $ ("div" ).html ("<p> Nice to meet you </p> ");
Result: [<div> <p> Nice to meet you </p> </div>]

Second, there are two methods in the text attribute: one with a parameter and the other without a parameter.
1. No parameter text (): obtains the content of all matching elements. The result is a combination of text content contained by all matching elements. Returns a String
Example:
Html page code: <p> <B> Hello </B> fine </p>
<P> Thank you! </P>
Jquery code: $ ("p"). text ();
Result: HellofineThankyou!

2. text (val): Set the text content of all matching elements, similar to html, however, encode HTML (replace "<" and ">" with the corresponding HTML Entity ). returns a jquery object.
Html page code: <p> Test Paragraph. </p>
Jquery code: $ ("p"). text ("<B> Some </B> new text .");
Result: [<p> <B> Some </B> new text. </p>]

Finally, there are two methods in the val () attribute, one with a parameter and the other without a parameter.
1. No parameter val (): obtains the current value of the First Matching Element. In jQuery 1.2, the value of any element can be returned. Including select. If multiple values are selected, an array containing the selected values is returned.
Returns a String, array
Example:
Html page code:
Copy codeThe Code is as follows:
<P> </p> <br/>
<Select id = "single">
<Option> Single </option>
<Option> Single2 </option>
</Select>
<Select id = "multiple" multiple = "multiple">
<Option selected = "selected"> Multiple </option>
<Option> Multiple2 </option>
<Option selected = "selected"> Multiple3 </option>
</Select>

Jquery code: $ ("p "). append ("<B> Single: </B>" + $ ("# single "). val () + "<B> Multiple: </B>" + $ ("# multiple "). val (). join (","));
Result: [<p> <B> Single: </B> Single <B> Multiple: </B> Multiple, Multiple3 </p>]
2. val (val): sets the value of each matching element. In jQuery 1.2, this can also assign values to check, select, and radio elements, and return a jquery object.
Html page code:
<Input type = "text"/>
Jquery code: $ ("input"). val ("hello world! ");
Result: hello world!