如何从Firebase数据库中的对象获取数据？

Question

I have the following structure on my firebase database , what i want is that when ever user clicks on submit , it retrieves all the ads with that specified category value since i have pushed category(option) value to fire base database ie 1,2,3,4.

Fire base structure:

and my html code is :

<form class=" jumbotron browseCategory bs1">
    <h3 class="catSearch">SEARCH ADS USING CATEGORY SEARCH</h3> <br/> <hr/>
        <div class="form-group">
                    <label for="formGroupExampleInput2"> Select your category : </label>
                <select id="myselect">
                    <option value="1">Mobile</option>
                    <option value="2">Electronics</option>
                    <option value="3">Property</option>
                    <option value="4">Cosmetics</option>
                  </select> </div>
 <button type="submit" class="btn btn-primary" id="submission_cat">Search Ad of this Category</button>
    </form>

Answer 1

To filter ads by adCategory you may use:

  let ref = firebase.database().ref("ADS");
    ref.orderByChild("adCategory").equalTo("1").on("child_added", function(snapshot) {  
    console.log(snapshot.key);
    });

and hook it up to your submit handler function