Number: Fix integer and fraction formatter for small numbers like 1e-7

Fixes globalizejs#750

Author: rxaviers

src/number/format/integer-fraction-digits.js

@@ -35,6 +35,14 @@ return function( number, minimumIntegerDigits, minimumFractionDigits, maximumFra
 			number = round( number, { exponent: -maximumFractionDigits } );
 		}
 
+		// Use toFixed( maximumFractionDigits ) to make sure small numbers like 1e-7 are displayed
+		// using plain digits instead of scientific notation.
+		// 1: Remove leading decimal zeros.
+		// 2: Remove leading decimal separator.
+		number = number.toFixed( maximumFractionDigits )
+			.replace( /0+$/, "" ) /* 1 */
+			.replace( /\.$/, "" ) /* 2 */;
+
 		// Minimum fraction digits
 		if ( minimumFractionDigits ) {
 			number = String( number ).split( "." );
@@ -43,10 +51,9 @@ return function( number, minimumIntegerDigits, minimumFractionDigits, maximumFra
 		}
 	} else {
 		number = round( number );
+		number = String( number );
 	}
 
-	number = String( number );
-
 	// Minimum integer digits
 	if ( minimumIntegerDigits ) {
 		number = number.split( "." );

test/unit/number/format/integer-fraction-digits.js

@@ -74,4 +74,11 @@ QUnit.test( "should handle inaccurate floating point arithmetics", function( ass
 	assert.equal( formatIntegerFractionDigits( 0.00015, 1, 1, 4, round, null ), "0.0002" );
 });
 
+// `2e-7` => `"2,e-7"` (#750)
+QUnit.test( "should handle small numbers", function( assert ) {
+	assert.equal( formatIntegerFractionDigits( 2e-7, 1, 0, 10, round, null ), "0.0000002" );
+	assert.equal( formatIntegerFractionDigits( 1e-20, 1, 0, 20, round, null ), "0.00000000000000000001" );
+	assert.equal( formatIntegerFractionDigits( 9e-8, 1, 0, 7, round, null ), "0.0000001" );
+});
+
 });