Javascript tutorial 20 how to update array elements using map
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javascript tutorial 20: updating array elements with `map()`
this tutorial delves into the powerful `map()` method in javascript, specifically focusing on how it allows you to update elements within an array and create a new array with the modified values. we'll cover the basics of `map()`, its purpose, and then explore different scenarios where you might want to use it for updating array elements.
*understanding `map()`*
the `map()` method is a fundamental array method in javascript. it allows you to iterate over each element in an existing array, apply a transformation function to each element, and return a new array containing the results of those transformations. critically, the original array remains unchanged.
*syntax:*
*breakdown:*
`originalarray`: the array you want to iterate over and transform.
`map(callbackfunction)`: this is where the magic happens. the `map()` method takes a callback function as its argument. this callback function is executed *once for each element* in the `originalarray`.
`callbackfunction`: this function determines how each element is transformed. it receives up to three arguments:
`currentvalue`: the value of the current element being processed in the array. (required)
`index`: the index (position) of the current element in the array. (optional)
`array`: the `originalarray` itself. (optional, but rarely used)
the callback function **must return a value**. this returned value will become the corresponding element in the `newarray`.
`newarray`: the `map()` method returns a new array with the same length as the `originalarray`. each element in the `newarray` is the result of applying the `callbackfunction` to the corresponding element in the `originalarray`.
*why use `map()` for updating array elements?*
*immutability:* `map()` is a non-mutating method. this means it doesn't directly modify the original array. instead, it creates a new array with the ...
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