# Check If String Is a Prefix of Array

## 1961. Check If String Is a Prefix of Array

Given a string s and an array of strings words, determine whether s is a prefix string of words.

A string s is a prefix string of words if s can be made by concatenating the first k strings in words for some positive k no larger than words.length.

Return true if s is a prefix string of words, or false otherwise.

```### Example 1:
Input: s = "iloveleetcode", words = ["i","love","leetcode","apples"]
Output: true
Explanation:
s can be made by concatenating "i", "love", and "leetcode" together.
```
```### Example 2:
Input: s = "iloveleetcode", words = ["apples","i","love","leetcode"]
Output: false
Explanation:
It is impossible to make s using a prefix of arr.
```
```Constraints:
1 <= words.length <= 100
1 <= words[i].length <= 20
1 <= s.length <= 1000
words[i] and s consist of only lowercase English letters.
```
```/**
* @param {string} s
* @param {string[]} words
* @return {boolean}
*/
var isPrefixString = function(s, w) {
let wordStr = '';
for (let i = 0; i < w.length; i++) {
wordStr += w[i];
if (wordStr === s) {
return true;
} else if (wordStr.length > s.length) {
break;
}
}
return false;
};
```