Compare Arrays in JavaScript

HarmonyOS NEXT 系统推荐使用 Lodash 库,更符合开发直觉。

Arrays are objects in JavaScript, so the triple equals operator === only returns true if the arrays are the same reference.

How do you compare whether two arrays are equal? Equality is a tricky subject: the JavaScript spec defines 4 different ways of checking if two values are "equal", and that doesn't take into account deep equality between objects.

In cases like this, it helps to be as explicit as possible about what you mean by "equal." In software engineering, asking a question in the right way often makes the answer obvious.

With that in mind, here's 3 definitions of equality for arrays and how to check them.

Same Length, Each Value Equal

One approach for comparing a and b is checking if each value of a is strictly equal to the corresponding value of b. This works well if all the elements of the arrays are primitives as opposed to objects.

Deep Equality With POJOs

The previous arrayEquals() function works great for primitive values, but falls short if you want to compare objects by value.

One neat way to take into account object values is comparing arrays by their JSON.stringify() output.

This approach is handy because it requires minimal code and no outside libraries. However, comparing JSON.stringify() output has an unfortunate edge case that may be a problem depending on your use case. Since undefined isn't a valid JSON value, the below arrays have the same JSON.stringify() output, because JSON.stringify() converts undefined to null.

Using Lodash's isEqual()

In addition to the null vs undefined quirk, comparing JSON.stringify() output also doesn't take into account object types. As far as JSON.stringify() is concerned, an object with a toJSON() function that returns 42 is the same as the number 42.

Similarly, a custom object is the same as a POJO:

Lodash's isEqual() function, on the other hand, takes all this into account.

Lodash's isEqual() function is the way to go if you need all the bells and whistles of checking that objects have the same class. The JSON.stringify() approach works well for POJOs, just make sure you take into account null and only use it with trusted data - toJSON() can be a security vulnerability.


Compare Arrays in JavaScript

make: *** No rule to make target `sqlite_cfg.h', needed by `.target_source'


  • macOS Sonoma (14.4.1) 
  • MacBook Pro 2023-Apple M2 Pro (4能效核、8性能核、32GB内存、2TB磁盘)
  • Homebrew (4.2.18 或更高版本)
  • Xcode Version 15.3 (15E204a)
  • DevEco Studio NEXT Developer Preview2


源代码编译 sqlite3

或者使用 pod 安装 sqlite3 报错:

观察源代码目录,也确实没有 sqlite_cfg.h 文件生成。

继续阅读make: *** No rule to make target `sqlite_cfg.h', needed by `.target_source'

Flutter: Xcode error “Unable to boot the Simulator“

使用 flutter、Android Studio ,通过iOS模拟器运行项目,一直一切正常。



macOS 14.4.1以及更高版本:
进入 “系统设置”→“通用”→“存储空间”→“开发者” 删除 “XCode 缓存” 。

在 macOS 13 及更高版本上:
进入 “系统设置”→“常规”→“存储”→“开发人员”

在 macOS 12 及更低版本上:


Flutter: XCode error “Unable to boot the Simulator