Before asking this question, I looked into this,

I am not entirely sure if this is the correct one. If it is the correct one, the second issue is it is picking up the spaces. Even though I can replace the spaces later but I was wondering if there is a way to pick up the digits without spaces

var x = 'The cost of 2 burgers and 3 drinks are $15'
var y = x.match(/((?!([\$]))^)\d |(?:[^\$])\b\d /gm);
var z = y.toString().replace(/ /gm,'');

Thank you in advance.

CodePudding user response：

You could just use some standard js array / string manipulation to get the desired output:

const strings = [
  '2 burgers and 3 drinks would be $15',
  'The cost of 2 burgers and 3 drinks are $15',
  'The foo did bar to baz'
];

const results = strings.map(str => 
  (str.match(/.?\d /g) || [])  // Match all numbers with their preceding character
    .filter(s => s[0] !== '$') // Filter out matches that start with '$'
    .map(s => s.trim()));      // Trim the results.

console.log(results);

One massive advantage here is readability. If you come back to this code a year from now, it's pretty trivial to figure out what it does.

CodePudding user response：

You can extract the numbers by matching prices and matching and capturing other numbers while only collecting the latter:

var x = 'The cost of 2 burgers and 3 drinks are $15'
var re = /\$\d (?:\.\d )?|(\d (?:\.\d )?)/g
var output=[], m;
while (m =re.exec(x)) {
  if (m[1]) {
    output.push(m[1])
  }
}
console.log(output); // => [ "2",  "3" ]

See the regex demo. Here,

• \$\d (?:\.\d )? - matches $, one or more digits, and then an optional occurrence of . and one or more digits
• | - or
• (\d (?:\.\d )?) - Capturing group 1: one or more digits, and then an optional occurrence of . and one or more digits.

CodePudding user response：

If the digits should be preceded by a space, you can match either a space or assert the start of the string using (?:\s|^) and capture the digits in group 1 using (\d ).

Then you can extract the digits using group 1, which is denoted by m[1] in the example code.

(?:\s|^)(\d )

Regex demo

const regex = /(?:\s|^)(\d )/g;
[
  '2 burgers and 3 drinks would be $15',
  'The cost of 2 burgers and 3 drinks are $15'
].forEach(s => console.log(Array.from(s.matchAll(regex), m => m[1])))

If there can be an other character before it that is not a dollar sign or a digit to prevent a partial match.

(?:[^\d$]|^)(\d )

Regex demo

const regex = /(?:[^\d$]|^)(\d )/g;
[
  '2 burgers and 3 drinks would be $15',
  'The cost of 2 burgers and 3 drinks are $15 A12'
].forEach(s => console.log(Array.from(s.matchAll(regex), m => m[1])))

CodePudding user response：

I tend to favor the simplest approach.

If you are using JavaScript in IE11, then your RegEx options are pretty limited. The simplest option would be to use a regex that includes the $, then filter out numbers with a $ after the match:

const inputString = "5 hotdogs are $3, 7 eggs are $1 and 3 cheese blocks are $10";

const regexp = /(\$?\d )/g

console.log(
  inputString.match(regexp).filter( v => v[0] !== "$" )
);

The regex could be modified to include optional spaces, etc, but the principal holds. Sometimes the easiest approach to RegEx is to see it as a starting place rather than trying to make it give the final answer.