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JavaScript - check if array contains value
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In this article, we would like to show you how to check if array contains value using JavaScript.
Quick solution:
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const array = ['a', 'b', 'c'];2
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console.log(array.indexOf('b') !== -1); // trueHint: this solution works even in older web browsers and Node.js.
or:
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const array = ['a', 'b', 'c'];2
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console.log(array.includes('b')); // trueWarning:
Arrayincludes()was introduced in ES6 (around 2016).
In this example, we use includes() method to check if letters array contains specific characters.
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const letters = ['a', 'b', 'c'];2
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console.log(letters.indexOf('b') !== -1); // true4
console.log(letters.indexOf('x') !== -1); // falsewith numbers:
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const numbers = [1, 2, 3];2
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console.log(numbers.indexOf(1) !== -1); // true4
console.log(numbers.indexOf(4) !== -1); // falseIn this example, we use includes() method to check if letters array contains specific characters.
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const letters = ['a', 'b', 'c'];2
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console.log(letters.includes('b')); // true4
console.log(letters.includes('x')); // falsewith numbers:
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const numbers = [1, 2, 3];2
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console.log(numbers.includes(1)); // true4
console.log(numbers.includes(4)); // false
In this section, you can find a function that works in older and modern web browsers or Node.js.
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const containsItem = (array, item) => array.indexOf(item) !== -1;2
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// Usage example:5
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const letters = ['a', 'b', 'c'];7
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console.log(containsItem(letters, 'b')); // true9
console.log(containsItem(letters, 'x')); // false
