# Binary String
> Return a string giving the literal bit representation of a [double-precision floating-point number][ieee754].
## Usage
```javascript
var toBinaryString = require( '@stdlib/number/float64/base/to-binary-string' );
```
#### toBinaryString( x )
Returns a `string` giving the literal bit representation of a [double-precision floating-point number][ieee754].
```javascript
var str = toBinaryString( 4.0 );
// returns '0100000000010000000000000000000000000000000000000000000000000000'
str = toBinaryString( 3.141592653589793 );
// returns '0100000000001001001000011111101101010100010001000010110100011000'
str = toBinaryString( -1.0e308 );
// returns '1111111111100001110011001111001110000101111010111100100010100000'
```
The function handles [subnormals][subnormals].
```javascript
str = toBinaryString( -3.14e-320 );
// returns '1000000000000000000000000000000000000000000000000001100011010011'
str = toBinaryString( 5.0e-324 );
// returns '0000000000000000000000000000000000000000000000000000000000000001'
```
The function handles special values.
```javascript
str = toBinaryString( 0.0 );
// returns '0000000000000000000000000000000000000000000000000000000000000000'
str = toBinaryString( -0.0 );
// returns '1000000000000000000000000000000000000000000000000000000000000000'
str = toBinaryString( NaN );
// returns '0111111111111000000000000000000000000000000000000000000000000000'
str = toBinaryString( Infinity );
// returns '0111111111110000000000000000000000000000000000000000000000000000'
str = toBinaryString( -Infinity );
// returns '1111111111110000000000000000000000000000000000000000000000000000'
```
## Examples
```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var pow = require( '@stdlib/math/base/special/pow' );
var toBinaryString = require( '@stdlib/number/float64/base/to-binary-string' );
var frac;
var sign;
var exp;
var b;
var x;
var i;
// Convert random numbers to literal bit representations...
for ( i = 0; i < 100; i++ ) {
if ( randu() < 0.5 ) {
sign = -1.0;
} else {
sign = 1.0;
}
frac = randu() * 10.0;
exp = round( randu()*100.0 );
if ( randu() < 0.5 ) {
exp = -exp;
}
x = sign * frac * pow( 2.0, exp );
b = toBinaryString( x );
console.log( b );
}
```
[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
[subnormals]: https://en.wikipedia.org/wiki/Denormal_number