javascript - What's the most elegant way to cap a number to a segment?

Question

Let's say x, a and b are numbers. I need to limit x to the bounds of the segment [a, b].

In other words, I need a clamp function:

clamp(x) = max( a, min(x, b) )

Can anybody come up with a more readable version of this?

Answer 1

The way you do it is pretty standard. You can define a utility clamp function:

/**
 * Returns a number whose value is limited to the given range.
 *
 * Example: limit the output of this computation to between 0 and 255
 * (x * 255).clamp(0, 255)
 *
 * @param {Number} min The lower boundary of the output range
 * @param {Number} max The upper boundary of the output range
 * @returns A number in the range [min, max]
 * @type Number
 */
Number.prototype.clamp = function(min, max) {
  return Math.min(Math.max(this, min), max);
};

(Although extending language built-ins is generally frowned upon)