Match values in-between braces

I have a string like this: "hello %{name} good %{middle} bye".

I'm trying to find an effective way to extract out the values in-between the braces, so ideally I would end up with an array of ["name", "middle"].

Using match I can almost get there. The following returns: ['%{name}', '%{middle}']:

"hello %{name} good %{middle} bye".match(/%{([\w]+)}/g)

I'm not sure why it's including the %, {, and } characters in the return though.

How can I adjust my regular expression to only match name and middle?

Solution

You need to change your regex expression to capture the values inside the braces without the %, {, and } characters, you can modify it slightly.

Existing: /%{([\w]+)}/g => /%\{(\w+)\}/g

Refer the below examples:

const str = "hello %{name} good %{middle} bye";
const str1 = "hello %{aaa} good %{bbbb} bye";
const str2 = "hello %{xyz} %{gtr} %{pqr} bye";

const matches = str.match(/%\{(\w+)\}/g);
const matches1 = str1.match(/%\{(\w+)\}/g);
const matches2 = str2.match(/%\{(\w+)\}/g);

const values = matches.map(match => match.slice(2, -1));
const values1 = matches1.map(match => match.slice(2, -1));
const values2 = matches2.map(match => match.slice(2, -1));

console.log(JSON.stringify(values));
console.log(JSON.stringify(values1));
console.log(JSON.stringify(values2));

Also, this can be achieved via non regex-based approach as well:

const str = "hello %{name} %{world} %{middle} bye";
const str1 = "hello %{aaa} %{bye} %{bbbb} bye";
const str2 = "hello %{xyz} %{gtr} %{pqr} bye";
const startDelimiter = "%{";
const endDelimiter = "}";

function extractValues(input, startDelimiter, endDelimiter) {
    const values = [];
    let startIndex = 0;

    while ((startIndex = input.indexOf(startDelimiter, startIndex)) !== -1) {
        startIndex += startDelimiter.length;
        const endIndex = input.indexOf(endDelimiter, startIndex);
        if (endIndex === -1) {
            break; 
        }
        const value = input.substring(startIndex, endIndex);
        values.push(value);
        startIndex = endIndex + endDelimiter.length;
    }

    return values;
}

const result = extractValues(str, startDelimiter, endDelimiter);
const result1 = extractValues(str1, startDelimiter, endDelimiter);
const result2 = extractValues(str2, startDelimiter, endDelimiter);


console.log(JSON.stringify(result));
console.log(JSON.stringify(result1)); 
console.log(JSON.stringify(result2));