Question

How to create an empty array with predefined size in JavaScript

Answer 1

var arr = new Array(256);

arr[3] = 888;
arr[51] = 999;

document.write(arr[0] + "<br />");
document.write(arr[28] + "<br />");
document.write(arr[3] + "<br />");
document.write(arr[51] + "<br />");


    
    
/*
run:
     
undefined
undefined
888
999
     
*/

 

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Answer 2

var arr = new Array(256).fill(0);;

arr[3] = 888;
arr[51] = 999;

document.write(arr[0] + "<br />");
document.write(arr[28] + "<br />");
document.write(arr[3] + "<br />");
document.write(arr[51] + "<br />");


    
    
/*
run:
     
0
0
888
999
     
*/

 

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