How to implement regular replacement in javascript

Two methods to implement regular replacement in javascript: 1. Use the replace() function to replace a substring that matches the regular expression in the string. The syntax "String object.replace(/[\ r\n]/g,'replacement value')"; 2. Use the replaceAll() function to replace all substrings that match the regular expression in the string. The syntax is "String object.replaceAll(/[\r \n]/g,'replacement value')".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

Javascript provides two functions to implement regular replacement:

• replace() function

• replaceAll() function

1. Use the replace() function to implement regular replacement

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

string.replace(searchvalue,newvalue)

Parameter	Description
searchvalue	Required . A RegExp object that specifies the substring or pattern to be replaced. Note that if the value is a string, it is retrieved as a literal literal pattern rather than first being converted to a RegExp object.
newvalue	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.

Example 1: Use regular expressions to replace all lowercase "blue" with "red"

var str="Mr Blue has a blue house and a blue car";
console.log(str); 
var n=str.replace(/blue/g,"red");
console.log(n);

Example 2 : Use regular expressions to replace all newline characters with empty characters (that is, remove newline characters)

let a = '\n换行个阿斯蒂芬\r换行个阿斯蒂芬ABCD';
console.log(a);
let b = a.replace(/[\r\n]/g,'');
console.log(b);

2. Use the replaceAll() function to implement Regular replacement

replaceAll() is used to replace some characters with other characters in a string, or replace a substring that matches a regular expression. This function will replace all matching substring.

str.replaceAll(regexp|substr, newSubstr|function)

Parameter	Description
regexp|substr	must. A RegExp object that specifies the substring or pattern to be replaced. Note that if the value is a string, it is retrieved as a literal literal pattern rather than first being converted to a RegExp object. When using a regex, you must set the global ("g") flag, Otherwise, it raises TypeError: "replaceAll must be called with a global RegExp".
newSubstr|function	Required. A string value. Specifies functions for replacing text or generating replacement text.

Return value: a new string obtained by replacing all matches of regexp with newSubstr.

Example: Use regular expressions to replace all "blue" with "red"

var str="Mr Blue has a blue house and a blue car";
console.log(str); 
var n=str.replaceAll(/blue/ig,"red");
console.log(n);

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