将“ Hello”追加到数组javascript中每个项目的开头

Question

I have a homework problem asking me to map over the names array, and return a new array with "Hello," appended to the beginning of each name.

The elements are changed when run for the problem.

I have to use an arrow function, and also the map method. I'm having trouble finding how to use both the map method, while making sure it adds "Hello," to each element in the array.

This is the code and what I have so far.

Any suggestions?

var names = "TBD";

var formalGreeting = () => {
  names.map("Hello," + names)
};

So far this just adds the hello to the first element.

Answer 1

var names = ['John', 'Max', 'Ellie'];
var namesWithGreeting = (arr) => {
    return arr.map(name => "Hello " + name);
}

namesWithGreeting(names);
//Output: ['Hello John', 'Hello Max', 'Hello Ellie']

You pass in an array to your function, and then use the map method to iterate over all the names, returning a new array with all names concatenated with "Hello ".

Answer 2

This will work--

var a=["ashay","neeti"];
var e=(w)=>{return w.map(n=>"Hello "+n)};
alert(e(a));

Answer 3

The map() method calls a provided callback function once for each element in an array, in order, and constructs a new array from the results.

So in the following code snippet, we are mapping the array names where each element in the array is x an for each element we return back the element with the string Hello, appended before it.

As mentioned above, the map() does not mutate the current array that is being mapped but returns a new array so all we have to do now is assign the new array that you got from mapping names to the variable newNames .

 var names = ["A", "B", "C"]; var formalGreeting = (array) => { var newNames = array.map(x => { return "Hello," + x; }); console.log(newNames); }; formalGreeting(names);