查找选择器(Query Selector)

看到Github上的一个项目：

You Don’t Need jQuery

确实我们现在的开发环境如作者所说的已经改善了很多，目前已经出了很多新的节点查询方法。兼容到现代浏览器与IE10+。

大部分可以使用document.querySelectory(‘selector’)/document.querySelectorAll(‘selector’);

• document.querySelector 返回第一个值
• document.querySelectorAll 返回节点列表，可以通过[].slice.call(document.querySelectorAll(selector) || []); 转为数组。
• 1.0 Query by selector

  // jQuery
  $('selector');
  
  // Native
  document.querySelectorAll('selector');

• 1.1 Query by class

  // jQuery
  $('.class');
  
  // Native
  document.querySelectorAll('.class');
  
  // or
  document.getElementsByClassName('class');

• 1.2 Query by id

  // jQuery
  $('#id');
  
  // Native
  document.querySelector('#id');
  
  // or
  document.getElementById('id');

• 1.3 Query by attribute

  // jQuery
  $('a[target=_blank]');
  
  // Native
  document.querySelectorAll('a[target=_blank]');

• 1.4 Find sth.
  • Find nodes

    // jQuery
    $el.find('li');
    
    // Native
    el.querySelectorAll('li');

  • Find body

    // jQuery
    $('body');
    
    // Native
    document.body;

  • Find Attribute

    // jQuery
    $el.attr('foo');
    
    // Native
    e.getAttribute('foo');

  • Find data attribute

    // jQuery
    $el.data('foo');
    
    // Native
    // using getAttribute
    el.getAttribute('data-foo');
    // you can also use `dataset` if only need to support IE 11+
    el.dataset['foo'];

• 1.5 Sibling/Previous/Next Elements
  • Sibling elements

    // jQuery
    $el.siblings();
    
    // Native
    [].filter.call(el.parentNode.children, function(child) {
      return child !== el;
    });

  • Previous elements

    // jQuery
    $el.prev();
    
    // Native
    el.previousElementSibling;

  • Next elements

    // jQuery
    $el.next();
    
    // Native
    el.nextElementSibling;

• 1.6 ClosestReturn the first matched element by provided selector, traversing from current element to document.

  // jQuery
  $el.closest(selector);
  
  // Native - Only latest, NO IE
  el.closest(selector);
  
  // Native - IE10+ 
  function closest(el, selector) {
    const matchesSelector = el.matches || el.webkitMatchesSelector || el.mozMatchesSelector || el.msMatchesSelector;
  
    while (el) {
      if (matchesSelector.call(el, selector)) {
        return el;
      } else {
        el = el.parentElement;
      }
    }
    return null;
  }

• 1.7 Parents UntilGet the ancestors of each element in the current set of matched elements, up to but not including the element matched by the selector, DOM node, or jQuery object.

  // jQuery
  $el.parentsUntil(selector, filter);
  
  // Native
  function parentsUntil(el, selector, filter) {
    const result = [];
    const matchesSelector = el.matches || el.webkitMatchesSelector || el.mozMatchesSelector || el.msMatchesSelector;
  
    // match start from parent
    el = el.parentElement;
    while (el && !matchesSelector.call(el, selector)) {
      if (!filter) {
        result.push(el);
      } else {
        if (matchesSelector.call(el, filter)) {
          result.push(el);
        }
      }
      el = el.parentElement;
    }
    return result;
  }

• 1.8 Form
  • Input/Textarea

    // jQuery
    $('#my-input').val();
    
    // Native
    document.querySelector('#my-input').value;

  • Get index of e.currentTarget between .radio

    // jQuery
    $(e.currentTarget).index('.radio');
    
    // Native
    [].indexOf.call(document.querySelectAll('.radio'), e.currentTarget);

• 1.9 Iframe Contents$('iframe').contents() returns contentDocument for this specific iframe
  • Iframe contents

    // jQuery
    $iframe.contents();
    
    // Native
    iframe.contentDocument;

  • Iframe Query

    // jQuery
    $iframe.contents().find('.css');
    
    // Native
    iframe.contentDocument.querySelectorAll('.css');

今天先学习这个节点查询，后面继续学习其他部分以及探讨兼容性问题。

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