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The map() method of Array instances creates a new array populated with the results of calling a provided function on every element in the calling array.
map() creates a new array from calling a function for every array element. map() does not execute the function for empty elements. map() does not change the original array.
Array.prototype.map() is a built-in array method for iterating through the elements inside an array collection in JavaScript. Think of looping as a way to progress from one element to another in a list, while still maintaining the order and position of each element.
The JavaScript map() method is used to create a new array by applying a specified function to each element of the original array. This method does not modify the original array and is particularly useful for transforming or processing data stored in arrays.
Instead of manually iterating over the array using a loop, you can simply use the built-in Array.map() method. The Array.map() method allows you to iterate over an array and modify its elements using a callback function. The callback function will then be executed on each of the array's elements.
var doubledArray = array.map(function (nested) { return nested.map(function (element) { return element * 2; }); }); Furthermore, consider using es6 arrow functions: var doubledArray = array.map(nested => nested.map(element => element * 2));
map () 方法 创建一个新数组，这个新数组由原数组中的每个元素都调用一次提供的函数后的返回值组成。 为数组中的每个元素执行的函数。 它的返回值作为一个元素被添加为新数组中。 该函数被调用时将传入以下参数： 数组中当前正在处理的元素。 正在处理的元素在数组中的索引。 调用了 map () 的数组本身。 执行 callbackFn 时用作 this 的值。 参见 迭代方法。 一个新数组，每个元素都是回调函数的返回值。 map () 方法是一个 迭代方法。 它为数组中的每个元素调用一次提供的 callbackFn 函数，并用结果构建一个新数组。 callbackFn 仅在已分配值的数组索引处被调用。 它不会在 稀疏数组 中的空槽处被调用。 map () 方法是一个 复制方法。
The JavaScript Array map() method creates a new array that includes the results by applying a function to every element in the original array. Here’s the syntax of the map() method: map(callbackFn, thisArg);
Array.map is a function which is located on Array.prototype.map. The function does the following: Creates a new array with the same amount of entries/elements. Executes a callback function, this function receives and current array element as an argument and returns the entry for the new array. Returns the newly created array. Example: Basic usage:
The map() method creates a new array with the results of calling a function for every array element. Example let numbers = [2, 4, 6, 8, 10]; // function to return the square of a number function square(number) { return number * number; }