js判断只能输入

document.getElementById('myInput').addEventListener('input', function (e) {
    // 只允许数字
    this.value = this.value.replace(/[^0-9]/g, '');
});

document.getElementById('myInput').addEventListener('keypress', function (e) {
    // 只允许数字和小数点
    const char = String.fromCharCode(!e.charCode ? e.which : e.charCode);
    if (!/[0-9.]/.test(char)) {
        e.preventDefault();
    }
});

<input type="text" id="myInput" pattern="[0-9]+" title="只能输入数字">

$('#myForm').validate({
    rules: {
        myInput: {
            required: true,
            digits: true
        }
    },
    messages: {
        myInput: {
            required: "请输入数字",
            digits: "只能输入数字"
        }
    }
});