問題描述

根據文檔，有兩種方法可以獲取 ElementArrayFinder 中有多少元素(element.all() 調用的結果):

• $$(".myclass").length，記錄在 這里:

...數組的length等于ElementArrayFinder找到的元素的length，每個結果代表執行的結果對元素的操作.

• $$(".myclass").count()，記錄在 這里:

計算ElementArrayFinder所代表的元素個數.

這兩種方法有什么區別，應該首選哪一種?

$$(".myclass").length

需要解決 promise 以正確獲取元素的長度.

//工作$$(".myclass").then(function(items){項目長度；});//不工作$$(".myclass").length;

<小時>

$$(".myclass").count()

$$('.myclass').length 的包裝器，它本身就是一個 Promise，不需要像 .length 那樣解析 Promise

$$(".myclass").count();

<小時><塊引用>

應該首選哪一個?

除非在定位$$(".myclass")和.then(function(items){...})時涉及到一些復雜的業務，那么items.length 將提供更好的性能.

否則 $$(".myclass").count() 應始終使用.

According to the documentation, there are 2 ways to get how many elements are inside the ElementArrayFinder (the result of element.all() call):

• $$(".myclass").length, documented here:

...the array has length equal to the length of the elements found by the ElementArrayFinder and each result represents the result of performing the action on the element.

• $$(".myclass").count(), documented here:

Count the number of elements represented by the ElementArrayFinder.

What is the difference between these two methods and which one should be preferred?

$$(".myclass").length

Need to resolve the promise to get the length of element correctly.

// WORK
$$(".myclass").then(function(items){
  items.length;
});

// DOES NOT WORK
$$(".myclass").length; 

$$(".myclass").count()

A wrapper for $$('.myclass').length which being a promise itself and doesn't require to resolve promise like .length

$$(".myclass").count(); 

which one should be preferred?

Unless there some complex business when locating $$(".myclass") and .then(function(items){...}) involved then items.length will give better performance.

Otherwise $$(".myclass").count() should always be used.

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