JS: Array.prototype.map
arrayX.map(f)
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Apply function to every element of the array. Return the new array. Original array is not changed.
The function f is passed 3 args: • current_element • current_index • arrayX. arrayX.map(f, thisArg)
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Use thisArg for this Binding of f. If it is not given,
undefined
is used.
const a1 = [3,4,5]; const a2 = a1.map( (x => (x+1)) ); console.log(a2); // [ 4, 5, 6 ] // original is not changed console.log(a1); // [ 3, 4, 5 ]
Example of using second argument:
// example of using map with second argument function ff (x) { return [ x , this ] } console.log( [3,4,5].map( ff , 9 ) ); // [ [ 3, 9 ], [ 4, 9 ], [ 5, 9 ] ]