使用angularjs保留光标位置 [英] Preserving cursor position with angularjs

问题描述

以下代码段对 input 执行我想要的操作，即删除所有非字母数字字符，转换为大写，并保留光标位置.

The following snippet does what I want to an input, i.e., it removes all non-alphanumerical characters, converts to uppercase, and preserves the cursor position.

element = $(element);

element.keyup(function() {
    var x = element.val();
    var y = x && x.toUpperCase().replace(/[^A-Z\d]/g, '');
    if (x===y) return;
    var start = this.selectionStart;
    var end = this.selectionEnd + y.length - x.length;
    element.val(y);
    this.setSelectionRange(start, end);
});

我将此代码段放在指令的 link 中，它可以工作......主要是.

I placed this snippet in the link of a directive and it works.... mostly.

问题在于angular 模型在应用更改之前 看到了值.我尝试谷歌搜索如何使用 $apply 或 $digest 或其他任何东西，但没有任何效果.

The problem is that the angular model sees the value before the change gets applied. I tried to Google for how to use $apply or $digest or whatever here, but nothing worked.

(实际上，我以某种方式管理了它，但后来内容被重新渲染，我失去了位置.我无法复制它，但无论如何它还是不够好.)

(Actually, I somehow managed it, but then the content was re-rendered and I lost the position. I can't reproduce it, but it wasn't good enough, anyway.)

推荐答案

一种方法

• 输入只清理一次
• ngChange 然后只触发一次输入

• The input is only cleaned once
• ngChange on the input is then only fired once

是使用 ngModelController 的 $parsers 数组提供.它被设计为影响模型值的地方(通过其返回值)，但它也可以用作输入事件的侦听器.

is to use the $parsers array that the ngModelController provides. It's designed as a place to affect the model value (via its return value), but it also can be used as a listener to input events.

app.directive('cleanInput', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, ngModelController) {
      var el = element[0];

      function clean(x) {
        return x && x.toUpperCase().replace(/[^A-Z\d]/g, '');
      }

      ngModelController.$parsers.push(function(val) {
        var cleaned = clean(val);

        // Avoid infinite loop of $setViewValue <-> $parsers
        if (cleaned === val) return val;

        var start = el.selectionStart;
        var end = el.selectionEnd + cleaned.length - val.length;

        // element.val(cleaned) does not behave with
        // repeated invalid elements
        ngModelController.$setViewValue(cleaned);
        ngModelController.$render();

        el.setSelectionRange(start, end);
        return cleaned;
      });
    }
  }
});

然而，我不确定 $parsers 的这种用法是否有点黑客.该指令可以用作:

However, I'm not sure if this usage of $parsers is a bit of a hack. The directive can be used as:

<input type="text" clean-input ng-model="name">

或者如果你想要一个 ngChange 函数:

or if you would like an ngChange function:

<input type="text" clean-input ng-model="name" ng-change="onChange()">

在 http://plnkr.co/edit/dAJ46XmmC49wqTgdp2qz?p=preview

This can be seen in-action at http://plnkr.co/edit/dAJ46XmmC49wqTgdp2qz?p=preview

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