Easing Functions

easing.js

const easing = {
    easeInSine(t) {
        return -1 * Math.cos(t * (Math.PI / 2)) + 1;
    },
    easeOutSine(t) {
        return Math.sin(t * (Math.PI / 2));
    },
    easeInOutSine(t) {
        return -0.5 * (Math.cos(Math.PI * t) - 1);
    },
    easeInQuad(t) {
        return t * t;
    },
    easeOutQuad(t) {
        return t * (2 - t);
    },
    easeInOutQuad(t) {
        return t < 0.5 ? 2 * t * t : -1 + (4 - 2 * t) * t;
    },
    easeInCubic(t) {
        return t * t * t;
    },
    easeOutCubic(t) {
        var t1 = t - 1;
        return t1 * t1 * t1 + 1;
    },
    easeInOutCubic(t) {
        return t < 0.5 ? 4 * t * t * t : (t - 1) * (2 * t - 2) * (2 * t - 2) + 1;
    },
    easeInQuart(t) {
        return t * t * t * t;
    },
    easeOutQuart(t) {
        var t1 = t - 1;
        return 1 - t1 * t1 * t1 * t1;
    },
    easeInOutQuart(t) {
        var t1 = t - 1;
        return t < 0.5 ? 8 * t * t * t * t : 1 - 8 * t1 * t1 * t1 * t1;
    },
    easeInQuint(t) {
        return t * t * t * t * t;
    },
    easeOutQuint(t) {
        var t1 = t - 1;
        return 1 + t1 * t1 * t1 * t1 * t1;
    },
    easeInOutQuint(t) {
        var t1 = t - 1;
        return t < 0.5 ? 16 * t * t * t * t * t : 1 + 16 * t1 * t1 * t1 * t1 * t1;
    },
    easeInExpo(t) {
        if (t === 0) {
            return 0;
        }
        return Math.pow(2, 10 * (t - 1));
    },
    easeOutExpo(t) {
        if (t === 1) {
            return 1;
        }
        return -Math.pow(2, -10 * t) + 1;
    },
    easeInOutExpo(t) {
        if (t === 0 || t === 1) {
            return t;
        }
        var scaledTime = t * 2;
        var scaledTime1 = scaledTime - 1;
        if (scaledTime < 1) {
            return 0.5 * Math.pow(2, 10 * scaledTime1);
        }
        return 0.5 * (-Math.pow(2, -10 * scaledTime1) + 2);
    },
    easeInCirc(t) {
        var scaledTime = t / 1;
        return -1 * (Math.sqrt(1 - scaledTime * t) - 1);
    },
    easeOutCirc(t) {
        var t1 = t - 1;
        return Math.sqrt(1 - t1 * t1);
    },
    easeInOutCirc(t) {
        var scaledTime = t * 2;
        var scaledTime1 = scaledTime - 2;
        if (scaledTime < 1) {
            return -0.5 * (Math.sqrt(1 - scaledTime * scaledTime) - 1);
        }
        return 0.5 * (Math.sqrt(1 - scaledTime1 * scaledTime1) + 1);
    },
    easeInBack(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 1.70158 : arguments[1];
        var scaledTime = t / 1;
        return scaledTime * scaledTime * ((magnitude + 1) * scaledTime - magnitude);
    },
    easeOutBack(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 1.70158 : arguments[1];
        var scaledTime = t / 1 - 1;
        return scaledTime * scaledTime * ((magnitude + 1) * scaledTime + magnitude) + 1;
    }, easeInOutBack(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 1.70158 : arguments[1];
        var scaledTime = t * 2;
        var scaledTime2 = scaledTime - 2;
        var s = magnitude * 1.525;
        if (scaledTime < 1) {
            return 0.5 * scaledTime * scaledTime * ((s + 1) * scaledTime - s);
        }
        return 0.5 * (scaledTime2 * scaledTime2 * ((s + 1) * scaledTime2 + s) + 2);
    }, easeInElastic(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 0.7 : arguments[1];
        if (t === 0 || t === 1) {
            return t;
        }
        var scaledTime = t / 1;
        var scaledTime1 = scaledTime - 1;
        var p = 1 - magnitude;
        var s = p / (2 * Math.PI) * Math.asin(1);
        return -(Math.pow(2, 10 * scaledTime1) * Math.sin((scaledTime1 - s) * (2 * Math.PI) / p));
    },
    easeOutElastic(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 0.7 : arguments[1];
        var p = 1 - magnitude;
        var scaledTime = t * 2;

        if (t === 0 || t === 1) {
            return t;
        }
        var s = p / (2 * Math.PI) * Math.asin(1);
        return Math.pow(2, -10 * scaledTime) * Math.sin((scaledTime - s) * (2 * Math.PI) / p) + 1;
    }, easeInOutElastic(t) {
        var magnitude = arguments.length <= 1 || arguments[1] === undefined ? 0.65 : arguments[1];
        var p = 1 - magnitude;
        if (t === 0 || t === 1) {
            return t;
        }
        var scaledTime = t * 2;
        var scaledTime1 = scaledTime - 1;
        var s = p / (2 * Math.PI) * Math.asin(1);
        if (scaledTime < 1) {
            return -0.5 * (Math.pow(2, 10 * scaledTime1) * Math.sin((scaledTime1 - s) * (2 * Math.PI) / p));
        }
        return Math.pow(2, -10 * scaledTime1) * Math.sin((scaledTime1 - s) * (2 * Math.PI) / p) * 0.5 + 1;
    }, easeOutBounce(t) {
        var scaledTime = t / 1;
        if (scaledTime < 1 / 2.75) {
            return 7.5625 * scaledTime * scaledTime;
        } else if (scaledTime < 2 / 2.75) {
            var scaledTime2 = scaledTime - 1.5 / 2.75;
            return 7.5625 * scaledTime2 * scaledTime2 + 0.75;
        } else if (scaledTime < 2.5 / 2.75) {

            var _scaledTime = scaledTime - 2.25 / 2.75;
            return 7.5625 * _scaledTime * _scaledTime + 0.9375;
        } else {

            var _scaledTime2 = scaledTime - 2.625 / 2.75;
            return 7.5625 * _scaledTime2 * _scaledTime2 + 0.984375;
        }
    },
    easeInBounce(t) {
        return 1 - easeOutBounce(1 - t);
    },
    easeInOutBounce(t) {

        if (t < 0.5) {

            return easeInBounce(t * 2) * 0.5;
        }

        return easeOutBounce(t * 2 - 1) * 0.5 + 0.5;
    }
}