javascript - how can separate classes is begin with an underline?

Question

I fetch the classes of a <div> and save it in a variable.

this classes are following:

item drag drop img-circle _RS _CS ui-draggable ui-droppable ui-draggable-dragging

how can separate the classes that begins with an underline, like: _CS ?

Answer 1

您可以使用String.match它们来获得一个数组作为结果：

var classes = "_A drag drop img-circle _RS _CS ui-draggable a-_NASTY ui-xyz _z";
var underscoreClasses = classes.match(/(^| )_\S+/g);
console.log(underscoreClasses); // ["_A", " _RS", " _CS", " _z"]

如果您需要字符串（而不是数组），您可以使用Array.join它来实现：

var classes = "_A drag drop img-circle _RS _CS ui-draggable a-_NASTY ui-xyz _z";
var underscoreClasses2 = classes.match(/(^| )_\S+/g).join("");
console.log(underscoreClasses2); // "_A _RS _CS _z"

在这里演示 JsFiddle。

Answer 2

使用.split和.filter。

var classes = "item drag drop img-circle _RS _CS ui-draggable ui-droppable ui-draggable-dragging";
classes.split(/\s+/).filter(function(c) { return c[0] === "_"; })
=> ["_RS", "_CS"]

Answer 3

试试这个代码：

class = "item drag drop img-circle _RS _CS ui-draggable ui-droppable ui-draggable-dragging"
classes = class.split(" ")
underscoreclasses = []
$.each(classes, function(id, value) {
    if (value.slice(0, 1) == "_") {
        underscoreclasses.push(value)
    }
})

console.log(underscroreclasses)

它使用的是split 方法和slice 方法。