课程: JavaScript: Maps and Sets

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Map: Keys and values methods

Map: Keys and values methods - JavaScript教程

课程: JavaScript: Maps and Sets

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Map: Keys and values methods

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- [Instructor] Before we discuss our next two methods, keys and values, we're going to quickly review what an iterator is and how it relates to our Map. In JavaScript, we iterate over collections frequently using array methods like Map or for each. An iterator is defined by the MDN documentation as an object which defines a sequence, and potentially returns a value upon its termination. The next method is applied to the iterator and it has two properties, value and done. With our Map, some of its methods return iterators which allow us to cycle through keys and values in the order that they were inserted within our Map. Let's start with the keys method. It returns an iterator object that allows us to cycle through all of the keys found in our Map. It's likely that you would utilize this method by creating a new variable and setting it equal to your Map and then apply the keys method. Then, when you wanted to iterate over the…

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