I am confused why this code results with name[0] being equal to "f" instead of "foo". I thought that when I passed ' ' to the split method "foo" would be the result.

var ar = [];
ar[0] = "foo bar";
ar[1] = "dumdumdum";

var name = ar[0].split(' ');
console.log(name[0]);

I am confused why this code results with name[0] being equal to "f" instead of "foo". I thought that when I passed ' ' to the split method "foo" would be the result.

var ar = [];
ar[0] = "foo bar";
ar[1] = "dumdumdum";

var name = ar[0].split(' ');
console.log(name[0]);

• javascript
• arrays
• split

• 3 Try it with a variable name other than name. Or put the code inside a function so that name is a local variable. There is a built-in global window.name property that is always a string, and your name is referencing that property, hence your array gets converted to a string and then name[0] gets the first character of that string. See also this question. – nnnnnn Commented Apr 22, 2017 at 3:23
• 1 "In browsers there is a global window.name property…". ;-) – RobG Commented Apr 22, 2017 at 3:32

4 Answers 4

• The variable name is reserved in browsers. If you were to go in the developer console (click f12), and type window.name, you would see that it either gives you "" or some other string result.

• Your previous code ar[0].split(' '); is going to return the following array:

  [
     "foo",
     "bar"
  ]
  

• but the browser forcibly converts it to a string because your browser is mad at you since you are trying to change the typeof of its reserved variable ;), hence the string value "foo,bar". You might however get different results on different browsers.

• And doing name[0] to a string value of "foo,bar" gets the first letter of the string, f

"name" refers to window.name and is in use. so your array bees a string.

Use another variable such as array2

var ar = [];
ar[0] = "foo bar";
ar[1] = "dumdumdum";

var name2 = ar[0].split(' ');
console.log(name2[0]);

Wrap it in a function, you will get exactly result because name refer to window.name

(function () {
    var ar = [];
    ar[0] = "foo bar";
    ar[1] = "dumdumdum";

    var name = ar[0].split(' ');
    console.log(name[0]);
})()

You should avoid using the name as a variable, as this is an existing JavaScript built-in objects, properties, and methods. Your code should work after you rename the variable name to anything else, check the code belopw.

Your var name = ar[0].split(' '); returns an array of substrings.

var ar = [];
ar[0] = "foo bar";
ar[1] = "dumdumdum";

var changeThisVariableName = ar[0].split(' ');  
console.log(changeThisVariableName[0]);