[JQuery] 判斷Checkbox 是否被選取

HTML:

<input type="checkbox" name="check_mid" style="width:30px; height:30px;">
<button type="button" class="btn btn-primary" onclick="Search_Material()">查詢</button>

JS:

function Search_Material() {

    var check_mid = $('input[name="check_mid"]').prop("checked"); 
    alert(check_mid);　//有選取值=true，沒有選取值=false
}