How Do I Convert a Float to an Integer Effectively in JavaScript?

How to Convert a Float to an Integer in JavaScript

Converting a float to an integer in JavaScript is a common task for rounding numeric values. Here are the different methods you can use to perform this conversion efficiently, without relying on string conversion techniques.

Truncation

Truncation rounds a float towards negative infinity, discarding any fractional part. This can be achieved using the Math.floor() method:

<code class="javascript">var intvalue = Math.floor(floatvalue);</code>

Rounding

Rounding rounds a float to the nearest integer. If the fractional part is exactly 0.5, the value is rounded to the nearest even integer. The Math.round() method can be used for this purpose:

<code class="javascript">var intvalue = Math.round(floatvalue);</code>

Ceil

Ceil rounds a float upwards to the nearest integer. This is similar to rounding, except that it always rounds up, regardless of the fractional part. The Math.ceil() method can be used for this:

<code class="javascript">var intvalue = Math.ceil(floatvalue);</code>

ECMAScript 6's Math.trunc()

The ECMAScript 6 standard introduced a new method, Math.trunc(), which explicitly truncates a float to an integer without rounding:

<code class="javascript">var intvalue = Math.trunc(floatvalue);</code>

Bitwise Operators

Bitwise operators can also be used to truncate a float in JavaScript:

• ~~: This operator performs a bitwise operation that coerces the float to an integer by removing the fractional part.
• floatvalue | 0 and floatvalue >> 0: These operations also effectively truncate the float to an integer.

Examples

Here are some examples of converting floats to integers using different methods:

Method	Positive Float (5.5)	Positive Large Float	Negative Float (-5.5)	Large Negative Float
Math.floor	5	900719925474099	-6	-900719925474100
Math.ceil	6	900719925474100	-5	-900719925474099
Math.round	6	900719925474100	-6	-900719925474100
Math.trunc	5	900719925474099	-5	-900719925474099
~~	5	858993459	-5	-858993459

Math Object Reference

For more information on the Math object and its methods, refer to the [MDN web docs](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math).

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