Arrays

Array.prototype.sort()

Sort and reorder the items in an array. It modifies the original array, and by default will order the items alphanumerically.

let wizards = ['Merlin', 42, 'Gandalf', 2022, 'Radagast'];

// Sort the wizard array
// [2022, 42, "Gandalf", "Merlin", "Radagast"]
wizards.sort();

You can optionally pass in a callback function that will modify the default sorting behavior.

The Array.prototype.sort() method loops through each item, and passes two items at a time as arguments into the callback function. You can compare those two items, and return an integer telling Array.prototype.sort() what to do with them.

If you return -1, it will place the first item before the second one. If you return 1, it will move the second item before the current one. If you return 0 (or nothing at all), it will leave them unchanged.

let trees = [
	{
		type: 'White pine',
		pineCones: 4
	},
	{
		type: 'Blue spruce',
		pineCones: 3
	},
	{
		type: 'Douglas fir',
		pineCones: 7
	}
];

// sort the array so that the tree with the most pine cones is first, 
// and the one with the least pine cones is last
trees.sort(function (tree1, tree2) {

	// If the tree1 has more pine cones, put it before tree2
	if (tree1.pineCones > tree2.pineCones) {
		return -1;
	}

	// Otherwise, put tree2 before tree1
	return 1;

});

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