I try to chain some array and string methods but it doesn't work. It'd be great if anyone could explain to me why a function such as this doesn't work:
const scream = text => text.split('').push('!').join('').toUpperCase()
4 Answers
You could use Array#concat to return an array with another value instead of Array#push, which returns the new length, but is not part of a fluent interface for a later joining (which needs an array).
const scream = text => text.split('').concat('!').join('').toUpperCase();
console.log(scream('hi'));Comments
Push doesn't return the array. Here's an example that demonstrates what's happening with push, and shows another way to do it:
const scream = text => text.split('').push('!').join('').toUpperCase()
const test = ['a', 'b', 'c'];
const result = test.push('!')
console.log(result)
const newScream = text => [
...text,
'!'
].join('').toUpperCase()
newScream('hello')
console.log(newScream('hello'))
Comments
If you want to add 1 ! at the end:
const scream = text => text.split('').concat('!').join('').toUpperCase();
If you want to add it after each letter:
const scream = text => text.split('').map(e => e + '!').join('').toUpperCase();
The push don't return array, so join is not called on array in your case.
Comments
If you want to add character/string at the end of string use concat(<ch>) function. If you want to change case to upper then use toUpperCase() function.
Or
Simply you can use + operator to concat two strings and append ! to it.
var str = "Hello World";
var res = str.toUpperCase().concat("!");
var result = (str + '!').toUpperCase();
console.log(res);
console.log(result);
push(it does not return the array you pushed to, which should be clear if you look at the error that gets thrown)(text + '!').toUpperCase()