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How can I concatenate an array of numbers into 1 cascading number?

How do I join this array to give me the expected result in as few steps as possible?

var x = [31,31,3,1]
//expected output: x = 313131;
+6


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6 answers


Use array method join

. join

concatenates the elements of the array into a string and returns a string. The default delimiter is a comma (,). The separator here must be an empty string.



var  x = [31,31,3,1].join("");
+5


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I can't think of anything else but

+Function.call.apply(String.prototype.concat, x)

or if you insist

+''.concat.apply('', x)

In ES6:

+''.concat(...x)

Usage reduce

:



+x.reduce((a, b) => a + b, '');

Or if you prefer

x.reduce(Function.call.bind(String.prototype.concat), '')

Another idea is to manipulate the array like a string, always a good approach.

+String.prototype.replace.call(x, /,/g, '')

There may be other ways. Perhaps a Google search on "javascript array concatenation" will trigger some obscure function that concatenates the array elements.

+4


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Javascript join () will give expected output like string

. If you want it to be like number

, do this:

var x = [31,31,3,1];
var xAsString = x.join(''); // Results in a string
var xAsNumber = Number(x.join('')); // Results in a number, you can also use +(x.join(''))
+2


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Try join () like this

var x = [31,31,3,1]
var y = x.join('');
alert(y);
Run code


0


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Try below.

var x = [31,31,3,1]
var teststring = x.join("");
-2


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This will work

var x = [31,31,3,1];
var result = x.join("");
-2


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