To find the position of an element in an array, you use the indexOf() method. This method returns the index of the first occurrence the element that you want to ... ... <看更多>

In this tutorial we're going to learn about the # indexOf and #lastIndexOf # JavaScript Array Methods and how they can be used in order to ... ... <看更多>

https://msdn.microsoft.com/library/ff679977(v=vs.94).aspx. // https://developer.mozilla.org/es/docs/Web/JavaScript/Referencia/Objetos_globales/Array/indexOf. ... <看更多>

常會有找出陣列中是否包含某元素的需求，過去會使用Array.prototype.indexOf() 來處理，但在ES2016 (ES7) 提供了Array.prototype.includes() 新 ... ... <看更多>

The .indexOf() method is good for when you want to find the index of a primitive value inside your array (or a value which you already have ... ... <看更多>