How to tell if a string contains specific characters using JavaScript?

How to use JavaScript to determine whether a string contains specific characters?

In JavaScript, we can use several methods to determine whether a string contains specific characters. Three commonly used methods will be introduced below and corresponding code examples will be given.

Method 1: Use the indexOf() method
You can use the indexOf() method of the string to determine whether a string contains the specified characters. It returns the index of the first occurrence of a specific character in a string, or -1 if the character is not contained.

Sample code:

let str = "Hello, World!";
let char = "o";

if (str.indexOf(char) !== -1) {
    console.log("字符串包含特定字符");
} else {
    console.log("字符串不包含特定字符");
}

Method 2: Use the includes() method
Starting from ECMAScript 2016, JavaScript provides the includes() method, which can directly determine whether a string contains another string. a string. This method returns a Boolean value indicating whether the specified character was found.

Sample code:

let str = "Hello, World!";
let char = "o";

if (str.includes(char)) {
    console.log("字符串包含特定字符");
} else {
    console.log("字符串不包含特定字符");
}

Method 3: Using regular expressions
Regular expressions are a powerful pattern matching tool that can also be used to determine whether a string contains specific characters. .

Sample code:

let str = "Hello, World!";
let char = /o/;

if (str.match(char)) {
    console.log("字符串包含特定字符");
} else {
    console.log("字符串不包含特定字符");
}

The above are three commonly used methods to determine whether a string contains specific characters. According to actual needs and personal preferences, you can choose a method that suits you to complete string judgment. Hope this helps you!

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