使用JavaScript显示HTML文本框中剩余的字符数

This is my code:

这是我的代码:

function textCounter(field, countfield, maxlimit) {
    if (field.value.length > maxlimit) {
        field.value = field.value.substring(0, 160);
        field.blur();
        field.focus();
        return false;
    } else {
        countfield.value = maxlimit - field.value.length;
    }
}
function textCount