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Nicholas Lee
12,474 PointsWhat does this mean in javascript, return m === null ? 0 : m.length;
I am confused and not sure what this is called, I understand the regular expressions but don't know what ? or : mean.
function getVowels(str) {
var m = str.match(/[aeiou]/gi);
return m === null ? 0 : m.length;
}
2 Answers
Jenny Veens
10,896 PointsHi Nicholas,
This is a Ternary (or Conditional) return statement. It's like a short form for an if/else, and has nothing to do with regular expressions.
The first part of the statement is the condition (m === null). If the condition is true, the statement will return what's directly after the '?' ( 0, in this case ). If the condition is false, the statement will return the value after the ':' ( m.length ).
In this example a regex is checking for vowels in a string, and returning the number of vowels if any are found, otherwise it's returning 0.
alex novickis
34,894 Pointsexpression ? value_when_true : value_when_false
forms a ternary operator ( a fancy way of saying it takes three )
its a shorthand for this code in your case
if (m === null) {
return 0;
} else {
return m.length;
}