How to modify a certain value of a string in javascript

In JavaScript, you can use the replace() method to modify a certain value of a string. This method is used to replace some characters with other characters in a string, or to replace a substring that matches a regular expression. String, the syntax is "string.replace(regexp/substr, replaced value or function)".

The operating environment of this tutorial: Windows 10 system, JavaScript version 1.8.5, Dell G3 computer.

How to modify a certain value of a string in javascript

The replace() method is used to replace some characters with other characters in a string. , or replace a substring that matches a regular expression.

Syntax

stringObject.replace(regexp/substr,replacement)

Parameter Description

• regexp/substrRequired. A RegExp object that specifies the substring or pattern to be replaced. If the value is a string, it is retrieved as a literal literal pattern rather than first being converted to a RegExp object.

• replacement Required. A string value. Specifies functions for replacing text or generating replacement text.

Return value

A new string obtained by replacing the first match or all matches of regexp with replacement.

Explanation

The replace() method of string stringObject performs a search and replace operation. It will look for substrings in stringObject that match regexp and replace those substrings with replacement. If the regexp has the global flag g, then the replace() method replaces all matching substrings. Otherwise, it only replaces the first matching substring.

replacement can be a string or a function. If it is a string, then each match will be replaced by the string. But the $ character in replacement has a specific meaning. As shown in the following table, it illustrates that the string obtained from the pattern match will be used for replacement.

The example is as follows:

<script type="text/javascript">
var str="Visit city!"
document.write(str.replace(/city/, "School"))
</script>

Output result:

Visit School!

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