PHP表单中处理手机号码：提取、计数与验证

<form class="form" method="post" enctype="multipart/form-data">
    <div class="form-group row">
        <label for="title" class="col-lg-2 col-form-label">Mobile Numbers </label>                         
        <div class="col-lg-10">
            <textarea require  type="text" class="form-control required" required 
        cols="10" rows="7" id="mobileno" name="mobileno"> </textarea>
        </div>
    </div>

    <div class="form-group row">
        <label class="col-lg-2 control-label " for="userName">Number Count </label>
        <div class="col-lg-10">
            <input type="text" class="form-control " readonly id="numbercount" required name="numbercount" value="">
        </div>
    </div>

    <div class="form-group row">
        <div class="col-lg-12 text-center">
            <button id="btn" type="submit" name="submit" class="btn btn-success btn-lg waves-effect waves-light m-r-10">SUBMIT </button>
        </div>
    </div>
</form>

let numbers = document.querySelector('#mobileno');
let numbercount = document.querySelector('#numbercount');

addEventListener('mouseout', getNumbers);

function getNumbers(event) {
    event.preventDefault();
    let getnums = numbers.value.trim();
    getnums = getnums.split("\n");

    let result = "";
    let totalNum = 0;
    getnums.forEach(num => {
        if (num.length == 10 && num.indexOf("+") === -1) {
            result += num.substring(0, 10) + "\n";
            totalNum++;
        }
    });
    numbers.value = result;
    numbercount.value = totalNum;
}