input自适应长度

   <input type="number"   placeholder="请输入体重" id="patient-weight-input" oninput="changeWidth()"> 

function changeWidth() {
    var testLength = document.getElementById('patient-weight-input').value.length;
    var  testDom = document.getElementById('patient-weight-input');
    if(Number(testDom.value)>250){
        testDom.value=250
    }
    if(testLength){
        $("#patient-kg").show();
        if(testLength<4){
            testDom.style.width = testLength*0.24 + 'rem';
        }
    }else{
        $("#patient-kg").hide();
        testDom.style.width='100%';
    }
}