@jsmonday/imgproxy/index.js

ImgProxy Library for Node.js that works both on browser and server

const createHmac = require("create-hmac");
let PolyBuffer = Buffer;

if (typeof window !== "undefined") {
  PolyBuffer = require("buffer/").Buffer;
}
module.exports = class ImgProxy {
  constructor({ key, salt, url }) {
    this.options = {
      config: { key, salt, url },
      settings: {
        enlarge: 1,
        width: 1000,
        height: 1000,
        gravity: "ce",
        resizeType: "fill",
        extension: undefined,
        originalImage: undefined,
      },
    };
  }

  setOption(option, value) {
    this.options.settings[option] = value;
  }

  image(val) {
    this.setOption("originalImage", val);
    return this;
  }

  width(val) {
    this.setOption("width", val);
    return this;
  }

  height(val) {
    this.setOption("height", val);
    return this;
  }

  gravity(val) {
    this.setOption("gravity", val);
    return this;
  }

  enlarge(val) {
    this.setOption("enlarge", val);
    return this;
  }

  resizeType(val) {
    this.setOption("resizeType", val);
    return this;
  }

  extension(val) {
    this.setOption("extension", val);
    return this;
  }

  sign(target) {
    const hexKey = this.hexDecode(this.options.config.key);
    const hexSalt = this.hexDecode(this.options.config.salt);

    const hmac = createHmac("sha256", hexKey);
    hmac.update(hexSalt);
    hmac.update(target);
    return this.urlSafeBase64(hmac.digest());
  }

  hexDecode(hex) {
    return PolyBuffer.from(hex, "hex");
  }

  urlSafeBase64(string) {
    return PolyBuffer.from(string)
      .toString("base64")
      .replace(/=/g, "")
      .replace(/\+/g, "-")
      .replace(/\//g, "_");
  }

  get() {
    const settings = this.options.settings;
    const config = this.options.config;

    if (!settings.originalImage) {
      throw `Missing required param: image`;
    }

    const encoded_url = this.urlSafeBase64(settings.originalImage);
    const path = `/${settings.resizeType}/${settings.width}/${settings.height}/${settings.gravity}/${settings.enlarge}/${encoded_url}`;
    return `${config.url}/${this.sign(path)}${path}`;
  }
};