I have a 2D array and want to access with another array e.g:
var arr = [['one','two'],['three','four']];
var arr2 = [1,1];
I want to have the value at arr[arr2[0]][arr2[1]]. Is there another way to get the value, because if I do it that way, the row would get extrem long and hard to read.
Something like:
arr[arr2]
I know that this don't work but is there something similar in JavaScript?
You could reduce the array by using the indices, with a default array for not existent inner arrays.
function getValue(array, indices) {
return indices.reduce((a, i) => (a || [])[i], array);
}
var array = [['one', 'two'], ['three', 'four']],
indices = [1, 1];
console.log(getValue(array, indices));Use reduce with try/catch to ensure that doesn't have values which will throw error (for example, arr2 = [1,1,2,3,4] )
function evaluate(arr1, arr2)
{
try
{
return arr2.reduce( (a, c) => a[c], arr);
}
catch(e) {}
}
Demo
function evaluate(arr1, arr2) {
try {
return arr2.reduce((a, c) => a[c], arr)
} catch (e) {}
}
var arr = [['one','two'],['three','four']];
var arr2 = [1,1];
console.log(evaluate(arr, arr2))
try ... catch concept for exception, which is not necessary for the task.
Use arr[arr2[0]][arr2[1]] instead of arr[arr2]. Since, you only have two array values in your nested array for arr you can specify the index 0 and 1 for arr2 as a index of arr. Which is in the format arr[index1][index2]
var arr = [['one','two'],['three','four']];
var arr2 = [1,1];
console.log(arr[arr2[0]][arr2[1]]);You could use Array#reduce on arr2 and pass arr as the initial array.
Demo
let arr = [['one','two'],['three','four']],
arr2 = [1,1],
res = arr2.reduce((a,c) => a[c], arr);
console.log(res);This is an alternative:
A simple for-loop
var arr = [ ['one', 'two'], ['three', 'four'] ],
indexes = [1, 1];
Array.prototype.getFrom = function(indexes) {
var current;
for (var index of indexes) current = current ? current[index] : this[index];
return current;
}
console.log(arr.getFrom(indexes));.as-console-wrapper { max-height: 100% !important; top: 0; }<script src="https://codepen.io/egomezr/pen/dmLLwP.js"></script>
arr