自定义输入框输入的数字个数

$(function () {
$.fn.manhuaInputLetter = function (options) {
var defaults = {
len: 200,
showId: "show"
};
var options = $.extend(defaults, options);
var $input = $(this);
var $show = $("#" + options.showId);
$show.html(options.len);
$input.on("keydown keyup blur", function (e) {
var content = $(this).val();
var length = content.length;
var result = options.len - length;
if (result >= 0) {
$show.html(result);
} else {
$(this).val(content.substring(0, options.len))
}
});
}
});

Content.manhuaInputLetter({
len:45,
});