创建并排列，然后循环查找我然后提醒用户名

Question

Create an array and fill it with at least six usernames (ie “Sophia”, “Gabriel”, …) then loop through them with a for loop. If a username contains the letter “i” then alert the username.

I have tried to make an array and create and "if" statement, then I want to make an alert. I know I am missing something, but I can't figure out what.

  let userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john'];

  if(userNames.includes('i')){

    window.alert(userNames);
  }

I would like there to be a window alert with the name "mike"

Answer 1

Use a for loop if you want to return the index value of the array. In this case we treat the letter i as a regular expression by placing it between two forward slashes, and try to match that string in each array value. It then alerts you with the entire value (mike(

  let userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john']; for(let i = 0; i < userNames.length; i++) { if(userNames[i].match(/i/)) { window.alert(userNames[i]); } } 

Answer 2

That's not how includes works... for example:

const userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john'];

console.log(userNames.includes('mike')) // true
console.log(userNames.includes('i')) // false

To get what you want you can do something like this:

  const userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john']; userNames.forEach(name => { if(name.includes('i')) { console.log(name) } }) 

Answer 3

Iterate over the array with forEach then match it against a regular expression:

 const userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john']; const regex = /i/; userNames.forEach(name => { if (name.match(regex)) { alert(name); } }) 

Or you could use includes :

 const userNames = ['rachel', 'greg', 'mike', 'adam', 'susan', 'john']; userNames.forEach(name => { if (name.includes("i")) { alert(name); } })