I have two arrays:
var firstarray = [123, 13, 34, 12, 63, 63];
var secondarray = [[10,20,10], [122, 123, 53], [542, 234, 12, 331]];
I need to have a function that works something like this:
function checkArray(array){
//if array contains multiple arrays, return true
//if the array contains only values, return false
}
The number of arrays inside secondarray always varies.
Hint: Loop on the first array and determine if one of the object you're reading is an array.
Here is a function that could help you :
function is_array(input){
return typeof(input)=='object'&&(input instanceof Array);
}
Array(1, 2, 3) instanceof Array is true but '[1, 2, 3] instanceof Array' is false.
[1, 2, 3] instanceof Array returns trueIn modern Javascript:
myAry.every(Array.isArray) // returns true if all elements of myAry are arrays
References (and replacements for older browsers):
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/every
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/isArray
The main problem to this is that in JavaScript typeof anArrayVariable returns object as does typeof aRealObject - so there's no easy way to distinguish them.
jQuery fixes this to some extent with a method $.isArray() which correctly returns true for an array and false for an object, a number, a string or a boolean.
So, using jQuery this becomes as easy as:
function checkArray(array){
//if array contains multiple arrays, return true
//if the array contains only values, return false
for(var i=0;i<array.length;i++){
if($.isArray(array[i]))
return true;
}
return false;
}
I suggest you could take a look at the source for that method in jQuery and implement this same idea in vanilla javascript.
Check the type of the first element in the array:
function checkArray(list) {
return typeof(list[0]) == "object";
}
