Given a jQuery object that represents a set of DOM elements, the .prevAll() method searches through the predecessors of these elements in the DOM tree and construct a new jQuery object from the matching elements; the elements are returned in order beginning with the closest sibling.
The method optionally accepts a selector expression of the same type that we can pass to the $() function. If the selector is supplied, the elements will be filtered by testing whether they match it.
Consider a page with a simple list on it:
1 2 3 4 5 6 7 | <ul> <li>list item 1</li> <li>list item 2</li> <li class="third-item">list item 3</li> <li>list item 4</li> <li>list item 5</li></ul> |
If we begin at the third item, we can find the elements which come before it:
1 | $( "li.third-item" ).prevAll().css( "background-color", "red" ); |
The result of this call is a red background behind items 1 and 2. Since we do not supply a selector expression, these preceding elements are unequivocally included as part of the object. If we had supplied one, the elements would be tested for a match before they were included.
A string containing a selector expression to match elements against.
Locate all the divs preceding the last div and give them a class.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | <!doctype html><html lang="en"><head> <meta charset="utf-8"> <title>prevAll demo</title> <style> div { width: 70px; height: 70px; background: #abc; border: 2px solid black; margin: 10px; float: left; } div.before { border-color: red; } </style></head><body> <div></div><div></div><div></div><div></div> <script>$( "div:last" ).prevAll().addClass( "before" );</script> </body></html> |
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