Convert a Number to a String

By Stephen Bucaro

In many instances, Java Script automatically converts numbers to strings. For example, anytime you display a number using document.write or alert, Java Script automatically converts the number to a string for display.

var n = 10 + 2;
alert(n);

var n = 10 + 2;
document.write(n);

Both of the code snippets above will cause the string "12" to display.

A quick way to convert a number to a string is to use the string concatenation operator (+) as shown below.

var t = 118;
var s = t + " degrees f";
document.write(s);

The code above will display the string "118 degrees f".

You don't actually need any characters in the concatenated string to convert a number to a string, as shown below.

var n = 3.14152;
alert(typeof n);
n = 3.14152 + "";
alert(typeof n);

The fist message box will display the type of n as "number", after concatenating an empty string to the variable n, the second message box will display the type of n as "string".

The code below casts the number 3.14152 to a string by passing it to a String object constructor.

var n = 3.14152;
var s = String(n);
alert(typeof s);

The proper way to convert a number to a string is to use the Number object's toString method, as shown below.

var n = 3.14152;
s = n.toString();
alert(typeof s);

why would you want to convert a number to a string? After performing a calculation, you may need to format the result for display. The code shown below formats the number 32.6738 to $ 32.67 for display as a currency value.

var k = 32.6738;
m = k.toString();
var n = m.substring(0,m.indexOf(".") + 3);
var amt = "$ " + n;
alert(amt);

In many instances, Java Script automatically converts numbers to strings, but you can use the String object constructor or the toString method to explicitly convert a number to a string.

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