根据选择的选项值输入输入值 [英] Form input value based on option value selected

问题描述

以下表格

for the following form

<form action ='search.php' method = 'post'>

<select name="filter">
<option id="A" value="A">A</option>
<option id="B" value="B">B</option>
</select>

<input type ='text' name="key" id ="field" value ="something that changes based on what option is selected" />

<input type ='submit' value = 'Search' />

</form>

如何根据 A 或 B 是否被选中？我认为它必须在JavaScript中完成。我已经在这里和那里使用jQuery，所以可以根据它提出建议。

How do i make the value of the input field change based on whether A or B is selected? I assume it has to be done in javascript. I have used jquery here and there so it is ok to make suggestions based on it. Thanks alot!

推荐答案

您可以试试这个

<script type="text/javascript">
function changeValue(){
    var option=document.getElementById('filter').value;

    if(option=="A"){
            document.getElementById('field').value="A Selected";
    }
        else if(option=="B"){
            document.getElementById('field').value="B Selected";
        }

}
</script>
<form action ='search.php' method = 'post'>

    <select name="filter" id="filter" onchange="changeValue();">
<option id="A" value="A">A</option>
<option id="B" value="B">B</option>
</select>

<input type ='text' name="key" id ="field" value ="something that changes based on what option is selected" />

<input type ='submit' value = 'Search' />

</form>

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