JavaScript Array keys() Method17 Mar 2025 | 2 min read The keys() method creates and returns a new iterator object which holds the key for every index in the array. This method does not affect the original array. SyntaxParameterIt does not hold any parameter. ReturnIt returns a new array iterator object. JavaScript Array keys() ExampleLet's see some examples to understand better. Example1 Here's the simple implementation of keys() method in array. Test it NowOutput: ![]() So, according to the number of elements present in the array, a key is assigned to each one. Example2 Implementing keys() method with holes in between the array. Test it NowOutput: ![]() Note: It is clear from the above example that Array keys() method does not ignore the holes present as an array element in the given array. It assigns a key value to that empty hole too. Also, the keys are assigned in an increasing order sequence to each element.Example3 Test it NowOutput: ![]() Example4 Here's an example to generate keys for a user-define array. Test it NowOutput: Initially, the user will input the elements through prompt box which will be displayed as: ![]() After clicking on Get Keys button, the keys will be generated as: ![]() Thus, keys() method is a direct approach forgenerating keys for the array values. Next TopicJavaScript Array |
JavaScript Array method The JavaScript array method calls the specified function for every array element and returns the new array. This method doesn't change the original array. Syntax The method is represented by the following syntax: array.map(callback(currentvalue,index,arr),thisArg) Parameter callback - It represents the function that produces...
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JavaScript Array Method The JavaScript array method combines two or more arrays and returns a new string. This method doesn't make any change in the original array. Syntax The method is represented by the following syntax: array.concat(arr1,arr2,....,arrn) Parameter arr1,arr2,....,arrn - It represent the arrays to be combined. Return A new...
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JavaScript Array Method The method creates a new iterator object of an array, holding the key/value pairs for every value in the array. A key represents the index number carrying an item as its value. It does not affect the original array. Syntax The following syntax...
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JavaScript Array Method The method creates a string that represents the elements of an array. It converts the array elements into the string. Syntax array.; Parameter array: It is the given array or the source array. Including this, there are two optional parameters also. locales: It is a string that...
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JavaScript Array method The JavaScript array method combines all the elements of an array into a string and return a new string. We can use any type of separators to separate given array elements. Syntax The method is represented by the following syntax: array.join(separator) Parameter Separator() - It...
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JavaScript Array method The JavaScript array method is used to add/remove the elements to/from the existing array. It returns the removed elements from an array. The method also modifies the original array. Syntax The method is represented by the following syntax: array.splice(start,delete,element1,element2,?,elementn) Parameter start - It represents...
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JavaScript Array method The JavaScript array method fills the elements of the given array with the specified static values. This method modifies the original array. It returns undefined, if no element satisfies the condition. Syntax The method is represented by the following syntax: arr.fill(value[, start[, end]]) Parameter value...
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JavaScript Array method The JavaScript array method is used to arrange the array elements in some order. By default, method follows the ascending order. Syntax The method is represented by the following syntax: array.sort(compareFunction) Parameter compareFunction - It is optional. It represents a function that provides an...
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JavaScript Array method The JavaScript array method is used to search the position of a particular element in a given array. This method is case-sensitive. The index position of first element in an array is always start with zero. If an element is not present...
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JavaScript Array Method The method is an inbuilt array method that flattens a given array into a newly created one-dimensional array. It concatenates all the elements of the given multidimensional array, and flats upto the specified depth. We can specify the depth limit to...
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