web-utils-super/imgToBase64.js

前端函数库

/**
 * @desc: 将图片资源转为base64
 * @param {String} src 图片资源路径
 * @param {String} type 图片类型，默认img 只支持 'img'|'jpeg'| 'webp'
 * @param {Number} width 要生成的base64图片宽
 * @param {Number} height 要生成的base64图片高
 * @return {String}
 */
function imgToBase64(src, type = "png", width, height) {
  return new Promise((resolve, reject) => {
    let img = new Image();
    img.src = src;
    if (width) img.width = width;
    if (height) img.height = height;
    img.onload = () => {
      try {
        let canvas = document.createElement("canvas");
        canvas.width = img.width;
        canvas.height = img.height;
        let ctx = canvas.getContext("2d");
        ctx.drawImage(img, 0, 0, img.width, img.height);
        let dataURL = canvas.toDataURL(
          type.indexOf("image") > -1 ? type : `image/${type}`
        );
        resolve(dataURL);
      } catch (err) {
        reject(err);
      }
    };
  });
}

module.exports = imgToBase64;