Check if string is starting with prefix

Question

I would like to check with javascript if array items starts with the word "prefix".

So far I've done something like this:

let array = ["prefix-word1", "prefix-word2"];

array.forEach(function(element) {
      if (element.lastIndexOf('prefix', 0) == 0) {
        console.log('prefix');
      }
    }

For some reason I keep get an error that prefix is not defined. Please help.

Answer 1

This one works (check the comments on the code):

let array = ["prefix-word1", "prefix-word2" , "does not start with prefix"];

array.forEach(function(element) {
   // Check if the first word is prefix
   if (element.indexOf('prefix') == 0) {
     console.log('prefix');
     console.log(element);
   }
});
 
 console.log("Second approach which is not suggested");
 array.forEach(function(element) {
   // not the correct approach as suggested by @Barmar though it works
   if (element.lastIndexOf('prefix',0) == 0) {
     console.log('prefix');
     console.log(element);
   }
});