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Can't pass two dimensional array to new Map in Typescript:
const myArray: string[][] = [['DE', 'Germany'], ['AU', 'Austria']];
const myMap = new Map(myArray);
Fails to me with TS2769: No overload matches this call.
Am I doing something wrong here?
TS Version 3.9.9
403
Map Method for 2-dimensional Arrays Also called a map within a map: Sometimes you'll come across a multidimensional array -- that is, an array with nested arrays inside of it.
You can't specify different sizes in the declaration.
Use the Map() constructor to initialize a Map in TypeScript, e.g. const map1: Map<string, string> = new Map([['name', 'Tom']]) . The constructor takes an array containing nested arrays of key-value pairs, where the first element is the key and the second - the value. Copied!
To declare a 2D array, specify the type of elements that will be stored in the array, then ( [][] ) to show that it is a 2D array of that type, then at least one space, and then a name for the array. Note that the declarations below just name the variable and say what type of array it will reference.
If you dig through the log, you'll see an error message of
Target requires 2 element(s) but source may have fewer.
The problem is that ['DE', 'Germany'] gets automatically type-widened to string[] - an array of strings, which may have two elements, or one, or zero - but the Map constructor requires such entry arrays to have at least 2 elements. The type information that the number of items in the array is 2 gets lost.
I'd put the array declaration on the same line as the new Map:
const myMap = new Map([['DE', 'Germany'], ['AU', 'Austria']]);
Another option is
const arr: [string, string][] = [['DE', 'Germany'], ['AU', 'Austria']];
to show that the array actually does have 2 items in it.
Also note that you can't have a variable name start with a number - start it with something else, probably a letter.
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