javascript 下划线包含 (_.contains) 对象类型
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underscore contains (_.contains) on object types
提问by Crystal
I'm just getting started with Javascript and using the Underscore library. I see they have all sorts of utility function, like _.contains. Is there a way to make this work on objects?
我刚刚开始使用 Javascript 并使用 Underscore 库。我看到他们有各种各样的效用函数，比如 _.contains。有没有办法在对象上进行这项工作？
var indexes = [ {'id': 1, 'name': 'jake' }, {'id':4, 'name': 'jenny'}, {'id': 9, 'name': 'nick'}, {'id': 1, 'name': 'jake' }, {'id':4, 'name': 'jenny'} ];
if (_.contains(indexes, {'id':1, 'name': 'jake'})) {
console.log("contains");
}
Most of the examples they show have simple arrays with strings or numbers in them. I was wondering what I can do to use their utility functions like _.contains for objects. Thanks.
他们展示的大多数示例都有简单的数组，其中包含字符串或数字。我想知道我可以做些什么来使用他们的实用函数，比如 _.contains 用于对象。谢谢。
回答by loganfsmyth
containsrequires the values to be comparable with ===which will not work with different instances of objects.
contains要求这些值具有可比性，===这不适用于不同的对象实例。
For instance it would work if you passed the exact object you are searching for, which isn't very useful.
例如，如果您传递了您正在搜索的确切对象，它就会起作用，这不是很有用。
if (_.contains(indexes, indexes[0])) {
You can however use whereor findWhere.
但是，您可以使用where或findWhere。
if (_.findWhere(indexes, {'id':1, 'name': 'jake'})) {
findWhereis new in Underscore 1.4.4so if you do not have it, you can use where.
findWhere在 Underscore 中是新的，1.4.4所以如果你没有它，你可以使用where.
if (_.where(indexes, {'id':1, 'name': 'jake'}).length > 0) {
回答by mike
You would actually want to use _.wherefor this.
您实际上想为此使用_.where。
var indexes = [ {'id': 1, 'name': 'jake' }, {'id':4, 'name': 'jenny'}, {'id': 9, 'name': 'nick'}, {'id': 1, 'name': 'jake' }, {'id':4, 'name': 'jenny'} ];
if (_.where(indexes, {'id':1, 'name': 'jake'}).length) {
console.log("contains");
}
