Javascript和正则表达式替换文本

Question

Sir, I was doing a project with javascript .I want to replace a text with regex.in a paragraph i want to replace some word using javascript

eg:

 var str =" Would you like to have responses to your questions |code Would you like to have responses to your questions code| Would you like to have responses to your questions  "

 var n=str.replace("to","2");

Here all the " to " will be replaced.We don't want to remove between |code to code| Please help me any one.....

Answer 1

I think you shouldn't rely on regexps for these kind of tasks, since it would be overcomplicated and therefore slow. Anyway, if your expression is correct (ie, for every "|code" there's a "code|" and there aren't nested code tags), you can try this:

var n = str.replace(/to(?!(?:\|(?!code)|[^\|])*code\|)/g, "2");

Not only it's complicated, but it's hard to maintain. The best thing to do in these cases is to split your string to chunks:

var chunks = [], i, p = 0, q = 0;
while ((p = str.indexOf("|code", p)) !== -1) {
    if (q < p) chunks.push(str.substring(q, p));
    q = str.indexOf("code|", p);
    chunks.push(str.substring(p, p = q = q + 5));
}
if (q < str.length) chunks.push(str.substring(q));

// chunks === [" Would you like to have responses to your questions ",
//             "|code Would you like to have responses to your questions code|",
//             " Would you like to have responses to your questions  "]

Note: str.replace("to", "2") does not replace every occurrence of "to" , but only the first one.

Answer 2

if you want to replace all 'to' into 2 this will be the code

var str =" Would you like to have responses to your questions |code Would you like to have responses to your questions code| Would you like to have responses to your questions";
var n=str.replace(/to/g,"2");