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Using the map() array method

Using the map() array method - JavaScript教程

课程: JavaScript Essential Training

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Using the map() array method

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- [Instructor] The map method for arrays to serve special mention because it is heavily used when working with complex lists of data and when using frameworks like React. The map method takes an existing array, then does something to each of the items in the array and returns each of those items into a new array. In contrast, for each array method we looked at earlier loops through the array but doesn't create anything unless we explicitly tell it to and nothing is ever returned into something else. So if we need to create a new array with the items from an existing array and we want to change those items in the process, we use the map method. Looking at our foreach example from earlier, you see we use the foreach loop to loop through each of the items. Then we create a new element for each item, insert the item value into that element the "li" and then we append that item immediately to the stuff list ul so that it…

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