filter过滤器

Note: When a CSS selector string is passed to .filter(), text and comment nodes will always be removed from the resulting jQuery object during the filtering process. When a specific node or array of nodes are provided, a text or comment node will be included in the resulting jQuery object only if it matches one of the nodes in the filtering array.

We can also take advantage of the index passed through the function, which indicates the 0-based position of the element within the unfiltered set of matched elements:

filters中文

filter函数

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filter用法

The second form of this method allows us to filter elements against a function rather than a selector. For each element, if the function returns true (or a "truthy" value), the element will be included in the filtered set; otherwise, it will be excluded. Suppose we have a somewhat more involved HTML snippet:

Given a jQuery object that represents a set of DOM elements, the .filter() method constructs a new jQuery object from a subset of the matching elements. The supplied selector is tested against each element; all elements matching the selector will be included in the result.

This alteration to the code will cause the third and sixth list items to be highlighted, as it uses the modulus operator (%) to select every item with an index value that, when divided by 3, has a remainder of 2.

This code will alter the first list item only, as it contains exactly one tag. Within the filter function, this refers to each DOM element in turn. The parameter passed to the function tells us the index of that DOM element within the set matched by the jQuery object.