Example: Replace First Occurrence of a Character in a String
// program to replace a character of a string
const string = 'Mr Red has a red house and a red car';
// replace the characters
const newText = string.replace('red', 'blue');
// display the result
console.log(newText);
Output
Mr Red has a blue house and a red car
In the above program, the replace() method is used to replace the specified string with another string.
When a string is passed in the replace() method, it replaces only the first instance of the string. So if there is a second match in the string, it won't be replaced.
You could also pass a regular expression (regex) inside the replace() method to replace the string.
Example 2: Replace Character of a String Using RegEx
// program to replace a character of a string
const string = 'Mr Red has a red house and a red car';
// regex expression
const regex = /red/g;
// replace the characters
const newText = string.replace(regex, 'blue');
// display the result
console.log(newText);
Output
Mr Red has a blue house and a blue car
In the above program, a regex expression is used as the first parameter inside the replace() method.
/g refers to global. It means that all the matching characters in the string are replaced.
Since JavaScript is case-sensitive, R and r are treated as different values.
You could also use the regex to perform case-insensitive replacement using /gi, where i represents case-insensitive.