Search for Select Content in JS and select multiple

The company has a set of systems, and the Select menu stores too many categories. It is very difficult to find a category each time and a search is made.
I wrote comments for your reference.

form id =" form1 " name =" form1 " method =" Post " action =" ">

select name =" select " size =" 20 " id =" myselect " multiple =" multiple ">

Option value =" 11 "> 111444 Option >

Option value =" 22 "> 211144 Option >

Option value =" 33 "> 311155 Option >

Option value =" 44 "> 422355 Option >

<Option Value= "55">533333</Option>

</Select>

input name =" keywords " type =" text " id =" keywords ">

input type =" button " name =" button " id =" button " value =" Search for him " onclick =" selectone (document. getelementbyid ('keyword '). value) ">

</Form>

script language =" JavaScript ">

//ParametersKeywords ---InputKeywordSelectindex ---SpecifySelectIndex value of the Set

FunctionSelectone (keywords, selectindex)

{

KEYWORDS = keywords. Replace (// G,"")//Remove Spaces

var myselect = document. getelementbyid ( "myselect" ) // get the select Object

var J = 0; // Data Statistics

For(I = 0; I <myselect. length; I ++)//LoopOption

{

If(Myselect. Options [I]. Text. indexof (keywords )! =-1)//JudgmentOptionOfTextInclude or notKeyword

{

Myselect. Options [I]. Selected =True;//Selected

J ++;//Statistics

}

Else

{

Myselect. Options [I]. Selected =False;//Does not containKeywordsUnselect,If this clause is not added, it will be selected again

}

}

alert (" found " + J + " item " )

}

</Script>