Javascript - 提取位于两个特殊字符之间的字符串的一部分

Question

I have strings like these-

countries=a,b&states=c,d&districts=e,f,g,h
countries=a,b

I want to extract the part of the string which is lying between the characters = and & and return the result as an array. So, in the first case, the result should be ['a','b', 'c','d','e','f','g','h'] . In the second case, it should be ['a','b'] . I achieved the result by doing like this-

const extract = string.split('&');
const splitArray = extract.map(x => x.split('=')[1]);
const resultString = splitArray.join(',');
const result = resultString.split(',');

Can I do it more concisely and in a better way?

Answer 1

One example using URLSearchParams

let query = 'countries=a,b&states=c,d&districts=e,f,g,h';
let values = [];

(new URLSearchParams(query)).forEach(function(v) { 
    v.split(',').forEach(function(v){
        values.push(v);
    });
});

console.log(values); // ["a", "b", "c", "d", "e", "f", "g", "h"]

... but if by "concise" you mean "one-liner".. well here's my take:

let query = 'countries=a,b&states=c,d&districts=e,f,g,h';

query = query.replace(/(^|&).*?=/g,',').split(',').filter(Boolean);

console.log(query); // ["a", "b", "c", "d", "e", "f", "g", "h"]

Answer 2

 const input = [ 'countries=a,b&states=c,d&districts=e,f,g,h', 'countries=a,b' ]; input.forEach((line) => { let result = [].concat.apply([], line.split(/&/).map((keyValue) => { return keyValue.replace(/^[^=]*=/, '').split(/,/) })); console.log(line + ' ==> ' + JSON.stringify(result)); });

Output:

countries=a,b&states=c,d&districts=e,f,g,h ==> ["a","b","c","d","e","f","g","h"]
countries=a,b ==> ["a","b"]

Explanation:

• split by & to get key/value pairs
• for each key/value:
  • extract the value
  • split the value by '
• flatten the resulting array of arrays with [].concat.apply([], arr)

Alternatively you could initialize an empty array [] , and as a last step of for each key/value, do a forEach on each item, and push it to the array.