Some usage summaries of replace () in JavaScript

About definitions

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

About syntax

Stringobject.replace (regexp/substr,replacement)

About parameters

Parameters	Describe
Regexp/substr	Necessary. A RegExp object that specifies the substring or pattern to replace. Note that if the value is a string, it is used as the direct volume text pattern to be retrieved, instead of being converted to the RegExp object first.
Replacement	Necessary. A string value. A function that specifies replacement text or generates alternate text.

1, the first parameter regexp/substr, using the regular expression with the global identifier G, you can replace all matching substrings, otherwise it will only match once.

For example:

var str = "AAAAA"; var str1 = str.replace ("A", "B");
var str2 = str.replace (/a/g, "B");

　 operation Result: str1, "baaaa", str2, "BBBBB"

2. The second parameter, replacement, can be a string or function, or it can be a specific meaning that the $ character has.

character	Replace text
$, $ 、...、	The text that matches the 1th to 99th sub-expression in RegExp.
$&	A substring that matches the regexp.
$`	The text that is located to the left of the matching substring.
$	The text on the right side of the matching substring.
$$	Direct volume symbol.

A. examples of function:

var str = "111222AA"; str.replace (function(word) {    return "B";});

Run Result: "Bbaa"

Example of B. $

var str = "1234567890"/(\d{3}) (\d{3}) (\d{4})/g, "$1-$2-$3");

Operation Result: "123-456-7890"

Note: Most of the time, the combination of regexp and $ is used to achieve demand, so it is necessary to know some basic regular expression rules.

Some usage summaries of replace () in JavaScript