检查第一个字符串

Question

I'm a little bit confused with this task.

given the list="aaabcdefaabc" and word="abc".

You can see that list contain "abc" will make our answer 2 and 9

Can you give me some insight in javascript?

Answer 1

do you mean something like this?

let list="aaabcdefaabc"
matches = list.matchAll("abc")
for (let match of matches) console.log(match.index) // prints 2 and 9

EDIT: make a function returning the indices

With the help of this answer :

function searchIndices(str,pattern) {
   let matches = str.matchAll(pattern) // Object [RegExp String Iterator]
   matches = [...matches] // convert it to Array
   indices = matches.map(match => match.index) // get index from each match
   return indices
}
let ii = searchIndices("aaabcdefaabc","abc")
console.log(ii)

Answer 2

I'm not sure I understand the question.

Index could be found with indexOf and lastIndexOf.

let list="aaabcdefaabc"
console.log(list.indexOf("abc"))
// this print 2

console.log(list.lastIndexOf("abc"))
// this print 9

More documentation could be found here, https://www.w3schools.com/jsref/jsref_lastindexof.asp

This help you?