The replace() function in JavaScript is used to replace certain characters with other characters in a string. This function can accept two parameters, the first parameter can be a string or a regular expression, and the second parameter can be a string or a function.
1. Use a string as the first parameter:
In this case, the replace() function will use the string provided by the second parameter to replace the first parameter. Matching parts.
let str = 'Hello World'; let newStr = str.replace('World', 'JavaScript'); console.log(newStr); // 输出: 'Hello JavaScript'
2. Use a regular expression as the first parameter:
If you use a regular expression as the first parameter, the replace() function will use the characters provided by the second parameter. String or function to replace all matching parts.
Use a string as the second parameter:
let str = 'Hello World, Hello JavaScript'; let newStr = str.replace(/World/g, 'JavaScript'); console.log(newStr); // 输出: 'Hello JavaScript, Hello JavaScript'
In this example, /World/g is a regular expression, and the g flag indicates a global search, that is, finding all matching parts.
Use a function as the second parameter:
let str = 'Hello World, Hello JavaScript'; let newStr = str.replace(/World/g, function(matched) { return 'JavaScript'; }); console.log(newStr); // 输出: 'Hello JavaScript, Hello JavaScript'
In this example, the function accepts one parameter (in this case the matched string) and returns the string to be replaced.
Note: If the string contains special characters (such as $, ^, *, etc.), you need to use two slashes (\\) to escape when used as a regular expression. For example: 'Hello $'.replace(/\$/g, 'Java') will output 'Hello Java'.
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