


Detailed explanation of js replace and replaceall instance usage_javascript skills
stringObj.replace(rgExp, replaceText)
Parameters
stringObj
Required. The String object or string literal to perform this replacement on. The string will not be modified by the replace method.
rgExp
Required. Is a regular expression object containing a regular expression pattern or available flags. Can also be a String object or literal. If rgExp is not a regular expression object, it will be converted to a string and an exact search performed; do not attempt to convert the string to a regular expression.
replaceText
Required. Is a String object or string literal that replaces each matching position in rgExp in stringObj with the literal contained in the object. In Jscript 5.5 or newer, the replaceText parameter can also be a function that returns replacement text.
Explanation
The result of the replace method is a copy of the stringObj object that has completed the specified replacement.
Any of the following match variables can be used to identify the latest match and find the matching string. Match variables can be used in text replacements where the replacement string needs to be determined dynamically.
Character Meaning
$$ $ (JScript 5.5 or newer)
$& specifies the portion of stringObj that matches the entire pattern. (JScript 5.5 or newer)
$` specifies the part of stringObj preceding the match described by $&. (JScript 5.5 or newer)
$' specifies the part of stringObj after the match described by $&. (JScript 5.5 or newer)
$n captures the nth submatch, where n is a decimal digit from 1 to 9. (JScript 5.5 or newer)
$nn captures the nnth submatch, where nn is a decimal two-digit number from 01 to 99. (JScript 5.5 or newer)
If replaceText is a function, for each matched substring, the function is called with the following m 3 parameters, where m is the number of left brackets captured in rgExp number. The first parameter is the substring to match. The next m parameters are all results captured in the search. The m 2nd parameter is the offset within stringObj where the match occurs, and the m 3rd parameter is stringObj. The result is a string value with each matching substring replaced with the corresponding return value of the function call.
The Replace method updates the properties of the global RegExp object.
Example
The following example demonstrates the use of the replace method to replace the first occurrence of the word "The" with the word "A".
Function ReplaceDemo(){
var r, re ; // Declare variables.
var ss = "The man hit the ball with the bat.n";
ss = "while the fielder caught the ball with the glove.";
re = /The/g; // Create Regular expression pattern.
r = ss.replace(re, "A"); // Replace "The" with "A".
Return(r); // Return the replaced string.
}
In addition, the replace method can also replace subexpressions in the pattern. The following example demonstrates swapping each pair of words in a string:
Function ReplaceDemo(){
var r, re; // Declare variables.
var ss = "The rain in Spain falls mainly in the plain.";
re = /(S )(s )(S )/g; // Create a regular expression pattern.
r = ss.replace(re, "$3$2$1"); // Swap each pair of words.
Return(r); // Return the result string.
}
The following example (executed in JScript 5.5 and newer) performs a conversion from Fahrenheit to Celsius and demonstrates using the function as replaceText. To see how this function works, pass a string containing a numeric value followed by "F" (e.g. "Water boils at 212").
function f2c(s) {
var test = /(d (.d*)?)Fb/g; // Initialization mode.
return(s.replace
(test,
function($0,$1,$2) {
return((($1-32) * 5/9) "C");
}
)
);
}
document.write(f2c("Water freezes at 32F and boils at 212F."));
js actually does not provide it replaceAll method, using for loop has efficiency issues, giving you a regular expression solution
js code
String.prototype.replaceAll = function(s1,s2){
return this.replace(new RegExp(s1,"gm"),s2);
}
Method: string.replace(new RegExp(oldString,"gm"),newString))
gm g=global, m=multiLine, roughly the method is like this, you can replace all specified strings
Another simple method to verify JS:
Enter
in the browser address bar javascript:alert("abcabcabc".replace(new RegExp("a","gm"),"ad"))
This is easier;), I don’t know if it will be convenient for multiple lines
orgStr.replace(new RegExp(findStr, 'g'), replaceStr)
You should be able to replace all of them
If you don’t use regular expressions
orgStr.replace(findStr, replaceStr) can only replace the first one

The differences in performance and efficiency between Python and JavaScript are mainly reflected in: 1) As an interpreted language, Python runs slowly but has high development efficiency and is suitable for rapid prototype development; 2) JavaScript is limited to single thread in the browser, but multi-threading and asynchronous I/O can be used to improve performance in Node.js, and both have advantages in actual projects.

JavaScript originated in 1995 and was created by Brandon Ike, and realized the language into C. 1.C language provides high performance and system-level programming capabilities for JavaScript. 2. JavaScript's memory management and performance optimization rely on C language. 3. The cross-platform feature of C language helps JavaScript run efficiently on different operating systems.

JavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

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Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.


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