lib/strategy/strategy.js
function BackoffStrategy(options) {
    options = options || {};

    if (isDef(options.initialDelay) && options.initialDelay < 1) {
        throw new Error('The initial timeout must be greater than 0.');
    } else if (isDef(options.maxDelay) && options.maxDelay < 1) {
        throw new Error('The maximal timeout must be greater than 0.');
    }

    this.initialDelay_ = options.initialDelay || 100;
    this.maxDelay_ = options.maxDelay || 10000;

    if (this.maxDelay_ <= this.initialDelay_) {
        throw new Error('The maximal backoff delay must be ' +
                        'greater than the initial backoff delay.');
    }

    if (isDef(options.randomisationFactor) &&
        (options.randomisationFactor < 0 || options.randomisationFactor > 1)) {
        throw new Error('The randomisation factor must be between 0 and 1.');
    }

    this.randomisationFactor_ = options.randomisationFactor || 0;
}
function BackoffStrategy(options) {
    options = options || {};

    if (isDef(options.initialDelay) && options.initialDelay < 1) {
        throw new Error('The initial timeout must be greater than 0.');
    } else if (isDef(options.maxDelay) && options.maxDelay < 1) {
        throw new Error('The maximal timeout must be greater than 0.');
    }

    this.initialDelay_ = options.initialDelay || 100;
    this.maxDelay_ = options.maxDelay || 10000;

    if (this.maxDelay_ <= this.initialDelay_) {
        throw new Error('The maximal backoff delay must be ' +
                        'greater than the initial backoff delay.');
    }

    if (isDef(options.randomisationFactor) &&
        (options.randomisationFactor < 0 || options.randomisationFactor > 1)) {
        throw new Error('The randomisation factor must be between 0 and 1.');
    }

    this.randomisationFactor_ = options.randomisationFactor || 0;
}
Abstract class defining the skeleton for the backoff strategies. Accepts an object holding the options for the backoff strategy:  * `randomisationFactor`: The randomisation factor which must be between 0 and 1 where 1 equates to a randomization factor of 100% and 0 to no randomization. * `initialDelay`: The backoff initial delay in milliseconds. * `maxDelay`: The backoff maximal delay in milliseconds.