Join letters to 1 word

Question

I'm playing around with PEG.js.

This is my grammar:

start = expression

expression = a:[a-z]+
{return a.join("");}

When I execute it in my browser:

obj = parser.parse("test");
for (var i = 0; i <= obj.length; i++) {
    console.log(i + " - " + obj[i])
}

I get this output:

0 - t
1 - e
2 - s
3 - t
4 - undefined

Why isn't it joined to only 1 word, even though I used return a.join("") in my grammar?

Best guess: `parser.parse()` returns a string. What is the loop supposed to do? — JJJ, Oct 31 '15 at 18:53

score 1 · Answer 1 · answered Oct 31 '15 at 18:58

1

parser.parse does return the single word "test"; you are just printing it one character at a time.

Did you mean to do this?

var result = parser.parse("test");
console.log(result) // "test"

answered Oct 31 '15 at 18:58

joews

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score 1 · Answer 2 · answered Oct 31 '15 at 19:13

To directly answer your question, you're getting one letter each iteration because a string acts like an array. So you're accessing one letter at a time by using obj[i] Try this to get one word returned.

obj = parser.parse("test");
for (var i = 0; i <= obj.length; i++) {
    console.log(i + " - " + obj)
}

Join letters to 1 word

2 Answers2