How to realize single selection and multiple selection of select tags in HTML

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1. Basic usage:

Volvo

Saab

Opel

Audi

Among them, the tag can be omitted and used in the page.

All

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Online Learning Center of Chengdu normal University

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Second, you can select more than one Select element, as shown in the following code:

/ / if there is a multiple attribute, you can select more than one.

high school

University

doctor

/ / there is no multiple attribute below. Only one item is displayed. You cannot select more than one attribute.

high school

University

doctor

/ / the following is the case where the size attribute is set. If size=3 is set, then three pieces of data are displayed. Note that you cannot select more than one.

Primary school

Junior middle school

high school

Technical secondary school

Junior college

Undergraduate course

Graduate student

doctor

Postdoctoral

Please select

Third, all the common operations involved in selecting multiple Select components:

1. Determine whether there is an Item of the specified value in the select option

@ paramobjSelectId the id of the target select component to be verified

The value that @ paramobjItemValue will verify whether it exists

FunctionisSelectItemExit (objSelectId,objItemValue) {

VarobjSelect=document.getElementById (objSelectId)

VarisExit=false

If (nullroomroomobjSelectautomatically automatically typed of (objSelect)! = "undefined") {

For (vari=0;i