Detecting Whether an Array Contains an Item
var food = ["broccoli", "carrots", "spinach"]; var a = food.indexOf("spinach"); // a = 2 var b = food.indexOf("pizza"); // b = -1
The simplest way to check whether an item already exists in an array is to use the .indexOf(item). If the item is found, the index of the first instance is returned; otherwise, –1 is returned.
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