I'm currently exploring the differences between these two code snippets. Both of them flatten an array of subarrays and produce the same result.
Array.prototype.concatAll = function() {
var results = [];
this.forEach(function(subArray) {
subArray.forEach(function(element) {
results.push(element);
});
});
return results;
}; // [ [1,2,3], [4,5,6], [7,8,9] ] -> [1, 2, 3, 4, 5, 6, 7, 8, 9]
As well as
Array.prototype.concatAll = function() {
var results = [];
this.forEach(function(subArray) {
results.push.apply(results, subArray);
});
return results;
}; // [ [1,2,3], [4,5,6], [7,8,9] ] -> [1, 2, 3, 4, 5, 6, 7, 8, 9]
How exactly does apply function in this context? And why is results duplicated in that line?