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学ぶ The `includes` Method | Section
JavaScript Fundamentals

bookThe `includes` Method

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The includes method can be used to quickly determine of a specific element exists in the array or not.

Following is the general syntax of the includes method:

arrayName.includes(element);

The includes method returns a boolean (true or false) value based on whether or not the element exists in the array.

  • Returns true if the element is found;
  • Returns false if the element is not found.
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let itemsInStock = ["Laptop", "Phone", "Tablet", "Charger"]; console.log(itemsInStock.includes("Phone")); console.log(itemsInStock.includes("Headphones"));
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Note
Note

The includes method performs a strict comparison (===), meaning it checks for exact matches, including case sensitivity. For example, itemsInStock.includes("phone") would return false because "phone" (lowercase) is not the same as "Phone" (uppercase "P").

1. What will be the output of the following code?

2. Which of the following statements is true about the includes method?

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What will be the output of the following code?

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question mark

Which of the following statements is true about the includes method?

正しい答えを選んでください

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