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javascriptarrayspolymerweb-component

Convert a number (i. e. 5) to length of an array

I want to create a property on a polymer custom element that let's the user define a number of elements to repeat.

<my-element repeated-elements='5'></my-element>

This should tell my element to repeat the element inside of the component five times. For that I need an array with length of 5, so anything like this would do:

['','','','','']

Is there a way to do this in JavaScript? The number would be passed as a number, not a string. So somehow I would need to convert any number to the amount of array items in an array. Metaphorically speaking:

convertToArrayLength(5);

I'm completely lost here, I have no idea at all how this could be done.

Solution

  • The array constructor does exactly that:

    var arr = Array(5);

console.log(arr, arr.length);
//=> Array [ <5 empty slots> ] 5

    You don't need to put new before calling Array (just a peculiarity of the API).

    Note though that arrays in JavaScript are dynamic, so most of the time you don't need to specify the length of your array beforehand and can simply initialize your variable with:

    var arr = [];
// And then push to it as you go:
arr.push(x);