Linkage between the JS provincial and municipal drop-down lists

1. Define the urban data array
2. Get the selected Province
3. Obtain the location of the current province in the city array.
4. Obtain the prefecture-level cities under the jurisdiction of the current Province
5. Fill in the city drop-down list
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Example Code As follows: < Html >
< Head >
< Title > </ Title >
< Script Language = "JavaScript" Type = "Text/JavaScript" >
// Define a city data array
Cityarray =   New Array ();
Cityarray [ 0 ] =   New Array ( " Henan " , " Zhengzhou City | Kaifeng City | Luoyang City | Pingdingshan City | Anyang city | hebi city | Xinxiang City | Jiaozuo City | Puyang City | xuchang city | Luohe City | Sanmenxia City | Nanyang City | Shangqiu City | Xinyang City | Zhoukou City | Zhumadian City | Jiyuan City " );
Cityarray [ 1 ] =   New Array ( " Yunnan Province " , " Kunming City | Dali City | Qujing City | Yuxi city | Zhaotong City | Chuxiong City | Honghe city | Wenshan city | Simao City | Xishuangbanna city | Baoshan City | Dehong city | Lijiang City | Nujiang city | diqing city | Lincang City " );
Cityarray [ 2 ] =   New Array ( " Others " , " Others " );

Function Getcity (currprovince)
{
// Current Province
VaR Currprovince = Currprovince;
VaR I, J, K;
// Clear city drop-down list
Document. All. selcity. Length =   0 ;
For (I =   0 ; I < Cityarray. length; I ++ )
{
// Obtain the location of the current province in the city array.
If (Cityarray [I] [ 0 ] = Currprovince)
{
// Obtain the prefecture-level cities under the jurisdiction of the current Province
Tmpcityarray = Cityarray [I] [ 1 ]. Split ( " | " )
For (J = 0 ; J < Tmpcityarray. length; j ++ )
{
// Fill city drop-down list
Document. All. selcity. Options [document. All. selcity. Length] =   New Option (tmpcityarray [J], tmpcityarray [J]);
}
}  
}  
}
</ Script >
</ Head >
< Body >
< Form ID = "Form1" >
< Select ID = "Selprovince" Onchange = "Getcity (this. Options [This. selectedindex]. Value )" >
< Option Value = "" > -Select- </ Option >
< Option Value = "Henan Province" > Henan </ Option >
< Option Value = "Yunnan Province" > Yunnan Province </ Option >
< Option Value = "Others" > Others </ Option >
</ Select >

< Select ID = "Selcity" >
< Option > -City- </ Option >
</ Select >
</ Form >
</ Body >
</ Html >