Some functions for doing slope calculations that I wrote during my math class

slope.js

// uses https://github.com/ekg/fraction.js for displaying equation in fraction form
var Fraction = require('fractional').Fraction;

// returns the slope of a line in either a float or a string representation of a fraction, for reading.
// pass in two xy coordinate points and a boolean.
// if the boolean is true, it will return the fraction representation, and if false, a float.
// the xy coordinate points should be either arrays [x, y] or objects {x: 1, y: 1}
function slope(p1, p2, frac) {
    return frac ?
        new Fraction(((p2.y || p2[1]) - (p1.y || p1[1])), ((p2.x || p2[0]) - (p1.x || p1[0]))).toString()
    :
        ((p2.y || p2[1]) - (p1.y || p1[1])) / ((p2.x || p2[0]) - (p1.x || p1[0]))
};

// returns the y-intercept of the line.
// pass in the slope (m) and an xy coordinate point.
function yint(m, p) {
    return (p.y || p[1]) - (m * (p.x || p[0]))
};

// returns the equation of the line in y=mx+b format
// until I update this, it takes two xy coordinate points.
function equation(p1, p2) {
return 'y=' + slope(p1, p2, true) + 'x+' + yint(slope(p1, p2), p1)
};

I wrote this in my math class so I didn't have to do the tedious process of figuring out slope and y-int forty times. this is much easier.