Some easily overlooked points

Aug 10, 2022#技术42

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This post is translated from Chinese into English through AI.View Original

AI-generated summary

The article discusses some commonly overlooked points in programming, including setting default values for null objects, avoiding errors when using "for in" loops with non-object values, and dynamically accessing arrays through concatenation. The article provides code examples for these concepts.

If the value is null when listening to an object, an error will be thrown. Set the default value to {}.
Using "for in" can only iterate over objects. Writing "i in 4" is incorrect.
Dynamically retrieve array elements for concatenation and passing as parameters.

var arr = [
  "Unit1",
  "Unit2",
  "Unit3",
  "Unit4",
  "Unit5"
]

// 1. Array []
for (var i = 0; i < arr.length; i++) {
	this.defaultData.hostUnitList.push({
		[arr[i]]: this.defaultData[arr[i]]
	});
}

// 2. Object {}
for (var i = 0; i < arr.length; i++) {
	this.defaultData.hostUnitList[arr[i]] = this.defaultData[arr[i]]
}