Styjun

The var is set to an integer and as far as I know i++ means incrementing by 1. I do not understand why it prints all the characters of the variable sentence instead of all the integer that would correspond to the length.

var sentence = "I love learning software development";

for (var i=0; i < sentence.length; i++) 
	if (sentence[i] !== " ") 
		console.log(sentence[i]);
	

String Character access

There are two ways to access an individual character in a string. The first is the charAt() method:

return 'cat'.charAt(1); // returns "a"

The other way (introduced in ECMAScript 5) is to treat the string as an array-like object, where individual characters correspond to a numerical index:

return 'cat'[1]; // returns "a"

As others have stated, var sentence = "..." creates a collection or array of characters that you are then looping over.

A minor change in your code to help explain.

// Create a string (or an array of characters)
var sentence = "I love learning software development";

// Loop over the length of `sentence`.
// `i` is the index in the array from 0 to `sentence.length`
for (var i=0; i < sentence.length; i++) 
 if (sentence[i] !== " ") 
 console.log("char:["+ sentence[i] +"] i:["+ i +"]");
 

Your question is not entirely clear.

Do you want to print the index of every character that does not correspond to as space ("")?

If so, below would do that.

var sentence = "I love learning software development";

for (var i=0; i < sentence.length; i++) 
	if (sentence[i] !== " ") 
		console.log(i);
	

In the above code, I am printing the index, i, as long as the value at that index (i) is not a space character. Your code sentence[i] tells it to print the value at the index (i), which would be the character at that location in the string.

On the other hand if you want the Ascii value at index i, you need to use the charAt function: sentence.charAt[i].

var sentence = "I love learning software development";

for (var i=0; i < sentence.length; i++) 
	if (sentence[i] !== " ") 
		console.log(sentence.charCodeAt(i));
	

As another comment suggested, "...instead of all the integer that would correspond to the length" is unclear.

There is only 1 length for any given string. This is also true for any array at in any particular point in time.

Perhaps you mean index?

Each character has a unique index in any particular string.

To answer your question from the comments below:

index: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
sentence: I (space) l o v e (space) l e a r n i n g software development

There are a total of 36 characters in the sentence. (If I counted correctly)
index values start at 0 and end at 35
length is 36. But remember the last index number is 35, and the first is 0.

var sentence = "I love learning software development";

for (var i=0; i < sentence.length; i++) 
 console.log("index:", i, "character:", sentence.charAt(i));

console.log ("nlength: ", sentence.length, "index 0 - ", sentence.length-1);

Perhaps you are experienced in a different language where indexing a character of a string would return a integer.

In JavaScript, you get a human representation of the string. The string is initially encoded in UTF-16, converted into binary, and then stored in memory. However, when you access it, you get the actual string instead of UTF-16 code due to an language-specific automatic conversion.

However, if you are using Node.js you can use a buffer to store the string and deal with binary data directly.

In JavaScript, if you want to get the code you can use codePointAt(index) method:

alert( "z".codePointAt(0) ); // 122
alert( "Z".codePointAt(0) ); // 90