.preventDefault()无法正常工作.('input',function {})

Question

我想将可编辑div中的字符数限制为10.在用户达到限制后,我想使用.preventDefault()方法来保护div免受其他字符的影响.你能救我吗？JSFiddle https://jsfiddle.net/7x2dfgx6/1/ HTML

<div class="profileInfo" id="About" style="border:solid;" contenteditable="true">OOOOO</div>

JQuery的

    jQuery(document).ready(function($){

    const limit = 10;
    rem = limit - $('#About').text().length;
    $("#counter").append("You have <strong>" + rem + "</strong> chars left.");
    $("#About").on('input', function(event) {
        var char = $('#About').text().length;
        rem = limit - char;
        $("#counter").html("You have <strong>" + rem + "</strong> chars left.");
        if(char>limit)
        {
            event.preventDefault();
            //TODO
        }
    });
});

Answer 1

要回答你的主要问题:
.preventDefault()取消是事件的行为取消.input事件不是.

要检查是否event可取消,请尝试:console.log(event.cancelable);.
因为input它会说"假"

你可能想要这样的东西(未经测试):

const limit = 10;
var rem = limit - $('#About').text().length;
$("#counter").append("You have <strong>" + rem + "</strong> chars left.");
$("#About").on('input', function(event) {
    var char = $(this).text().length;
    rem = limit - char;
    if(rem <= 0){
        $(this).text($(this).text().slice(0, limit));
    }
    $("#counter").html("You have <strong>" + rem + "</strong> chars left.");
});

编辑

JSFiddle演示
由于它是contentEditable,我不得不使用额外的代码(来自这个答案)在输入的末尾设置一个插入符号.

Answer 2

使用keydown代替input

jQuery(document).ready(function($){

    const limit = 10;
    rem = limit - $('#About').text().length;
    $("#counter").append("You have <strong>" + rem + "</strong> chars left.");
    $("#About").on('keypress', function(event) {
        var char = $('#About').text().length;
        if(char>limit)
        {
            return false;
            //or
            event.preventDefault();
            //TODO
        }
        rem = limit - char;
        $("#counter").html("You have <strong>" + rem + "</strong> chars left.");

    });

});

演示