相当于LINQ Any()的JavaScript/jQuery

Is there an equivalent of IEnumerable.Any(Predicate<T>) in JavaScript or jQuery?

在JavaScript或jQuery中是否存在等价于IEnumerable.Any(谓词 ) ?

I am validating a list of items, and want to break early if error is detected. I could do it using $.each, but I need to use an external flag to see if the item was actually found:

我正在验证一个项目列表，如果检测到错误，我希望尽早中断。我可以用$。每个，但是我需要使用一个外部标志来查看项目是否被发现:

var found = false;
$.each(array, function(i) {
    if (notValid(array[i])) {
        found = true;
    }
    return !found;
});

What would be a better way? I don't like using plain for with JavaScript arrays because it iterates over all of its members, not just values.

还有什么更好的方法呢?我不喜欢在JavaScript数组中使用plain，因为它遍历所有成员，而不仅仅是值。

7 个解决方案

#1

These days you could actually use Array.prototype.some (specced in ES5) to get the same effect:

现在你可以使用Array.prototype了。有些(见ES5)会得到同样的效果:

array.some(function(item) {
    return notValid(item);
});

#2

You could use variant of jQuery is function which accepts a predicate:

您可以使用jQuery is函数的变体，它接受谓词:

$(array).is(function(index) {
    return notValid(this);
});

#3

You should use an ordinary for loop (not for ... in), which will only loop through array elements.

你应该使用一个普通的for循环(不是for…)在)中，它只会循环遍历数组元素。

#4

Xion's answer is correct. To expand upon his answer:

Xion的回答是正确的。进一步阐述他的回答:

jQuery's .is(function) has the same behavior as .NET's IEnumerable.Any(Predicate<T>).

jQuery的.is(函数)与。net的IEnumerable.Any(谓词 )具有相同的行为。

From http://docs.jquery.com/is:

从http://docs.jquery.com/is:

Checks the current selection against an expression and returns true, if at least one element of the selection fits the given expression.

如果选择中至少有一个元素符合给定的表达式，则根据表达式检查当前选择并返回true。

#5

I suggest you to use the $.grep() method. It's very close to IEnumerable.Any(Predicate<T>):

我建议您使用$.grep()方法。它非常接近于IEnumerable.Any(谓词 ):

$.grep(array, function(n, i) {
  return (n == 5);
});

Here a working sample to you: http://jsfiddle.net/ErickPetru/BYjcu/.

这里有一个工作示例:http://jsfiddle.net/ErickPetru/BYjcu/。

#6

I would suggest that you try the JavaScript for in loop. However, be aware that the syntax is quite different than what you get with a .net IEnumerable. Here is a small illustrative code sample.

我建议您尝试用JavaScript进行循环。但是，请注意，语法与.net IEnumerable是完全不同的。这是一个小型的说明性代码示例。

var names = ['Alice','Bob','Charlie','David'];
for (x in names)
{
    var name = names[x];
    alert('Hello, ' + name);
}

var cards = { HoleCard: 'Ace of Spades', VisibleCard='Five of Hearts' };
for (x in cards)
{
    var position = x;
    var card = card[x];
    alert('I have a card: ' + position + ': ' + card);
}

#7

You might use array.filter (IE 9+ see link below for more detail)

您可以使用数组。过滤器(ie9 +参见下面的链接以获得更详细的信息)

[].filter(function(){ return true|false ;}).length > 0;

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

#1