implement image validator

.eslintrc

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+{
+  "root": true,
+  "parser": "@typescript-eslint/parser",
+  "plugins": ["@typescript-eslint"],
+  "env": {
+    "es6": true,
+    "node": true,
+    "mocha": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended"
+  ],
+  "parserOptions": {
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
+  "rules": {
+    "no-console": "off",
+    "linebreak-style": "off",
+    "quotes": ["error", "double", { "allowTemplateLiterals": true }],
+    "keyword-spacing": ["error", { "before": true }],
+    "space-before-blocks": ["error"]
+  }
+}

.gitignore

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+node_modules
+.nyc_output
+coverage

.nycrc.json

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+{
+  "cache": false,
+  "check-coverage": true,
+  "extension": [".ts"],
+  "include": ["**/src/*.ts"],
+  "reporter": ["cobertura", "text-summary"],
+  "statements": 90,
+  "branches": 90,
+  "functions": 90,
+  "lines": 90
+}

dist/index.d.ts

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+/**
+ * This method validates a File (input) or an image URL
+ * @param src - The image to validate, an input File or a local or remote image url
+ * @param config - an optional config object that defines the method behaviour
+ * @returns - Returns true for valid images, throws or returns false for invalid images
+ */
+export declare const validateImage: (src: string | File, config?: {
+    throw: boolean;
+} | undefined) => Promise<boolean | undefined>;

dist/index.js

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+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.validateImage = void 0;
+/**
+ * This method validates a File (input) or an image URL
+ * @param src - The image to validate, an input File or a local or remote image url
+ * @param config - an optional config object that defines the method behaviour
+ * @returns - Returns true for valid images, throws or returns false for invalid images
+ */
+const validateImage = (src, config) => {
+    if (typeof window === "undefined") {
+        throw new Error("Cannot use this utility method in a non browser environment");
+    }
+    let url = "";
+    if (typeof src === "string") {
+        url = src;
+    }
+    else {
+        url = URL.createObjectURL(src);
+    }
+    const image = new Image();
+    image.src = url;
+    image.setAttribute("crossOrigin", "anonymous");
+    return new Promise((resolve, reject) => {
+        image.addEventListener("error", () => (config === null || config === void 0 ? void 0 : config.throw)
+            ? reject("The selected media resource is unsuitable")
+            : resolve(false));
+        image.addEventListener("load", () => resolve(true), false);
+    });
+};
+exports.validateImage = validateImage;