从常规数组创建新的2D数组

Question

If I have an JavaScript array:

a = ["12", "34", "56", "78"];

and I want to make a new 2D array like this:

b = [ ["12345678"], ["34567812"], ["56781234"], ["78123456"] ];

I know this should be pretty simple but I just can't figure it out... My brain is kinda slow today... :/

Answer 1

Join the string at various pivot locations.

n = [];
for(i = 0; i < a.length; i++){
    n.push(a.slice(i).join("") + a.slice(0,i).join(""));
}

This outputs:

[ "12345678", "34567812", "56781234", "78123456" ]

I am not certain whether having nested single element arrays in the output was a mistake, but if that is required just add square brackets inside push .

Answer 2

You can use map in conjunction with concat like this:

var newA = a.map(function() {
    var copy = a.slice();
    return [copy.concat(copy.splice(0, arguments[1])).join('')];
});

// => [ ["12345678"], ["34567812"], ["56781234"], ["78123456"] ];