Regex Experts!
Considering we have the following text, I'm attempting to find a REGEX to detect all TeX expressions enclosed by two $$s.
Select the correct answer:
a) 10 % = $$\frac{1}{10}$$.
b) 33 % < $$\frac{1}{3}$$
c) 2 % = $$\frac{2}{100}$$,
d) 9 % < $$\frac{1}{9}$$
e) 5 % = $$1+\frac{1}{5}$$
f) 1 % = $$0.05 - \frac{1}{5}$$
So far, what I have come up is:
/^\${2}[a-zA-Z0-9!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/ ?]*(\${2}|[\n\r]| )$/g
which, as you might have anticipated, shamefully isn't working! Here are a few issues I have: first, I am having difficulty to detect \frac or for that matter \. Although I have added \\, that still fails. Second, I am having problem with the fact that $$ could be followed by space, newline, , or . So even if I specify my expression to look for $$ at the end, that still won't catch many of cases.
I know I am not the first person who has ever attempted this so please share your thoughts or recommendations. Thanks in advance for your help!
Your ^\${2}[a-zA-Z0-9!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/ ?]*(\${2}|[\n\r]| )$ pattern is too verbose. Instead of whitelisting all possible chars there can appear in betweeb double dollar symbols, you may assume there may be any char there.
You may use
/\${2}.*?\${2}/g
Or - if there can be line breaks in between (which I doubt):
/\${2}[\s\S]*?\${2}/g
See the regex demo.
JS demo:
var rx = /\${2}.*?\${2}/g;
var str = "Select the correct answer:\n a) 10 % = \$\$\\frac{1}{10}\$\$.\n b) 33 % < $$\\frac{1}{3}$$\n c) 2 % = $$\\frac{2}{100}$$,\n d) 9 % < $$\\frac{1}{9}$$\n e) 5 % = $$1+\\frac{1}{5}$$\n f) 1 % = $$0.05 - \\frac{1}{5}$$";
console.log(str.match(rx));
// => ["$$\\frac{1}{10}$$","$$\\frac{1}{3}$$","$$\\frac{2}{100}$$","$$\\frac{1}{9}$$","$$1+\\frac{1}{5}$$","$$0.05 - \\frac{1}{5}$$"]
//or, to get what is inside
var rx_extract = /\${2}(.*?)\${2}/g;
var m, results = [];
while (m=rx_extract.exec(str)) {
results.push(m[1]);
}
console.log(results);
// => ["\\frac{1}{10}","\\frac{1}{3}","\\frac{2}{100}","\\frac{1}{9}","1+\\frac{1}{5}", "0.05 - \\frac{1}{5}"]