First version

.babelrc

+{
+    "presets": ["es2015"]
+}

.gitignore

+node_modules/

index.js

+export default function format(v, type='', str=''){
+    if(type === '' && str === ''){
+        return basicFormat(v);
+    }
+}
+
+/**
+ * Returns lower bound after which exponential format will be used
+ * @function getLowerBound
+ * @returns {Number}
+ */
+export function getLowerBound(){
+    return 1e-9;
+};
+
+/**
+ * Returns higher bound after which exponential format will be used
+ * @function getHigherBound
+ * @returns {Number}
+ */
+export function getHigherBound(){
+    return 1e+9;
+};
+
+
+export function basicFormat(x){
+    var lowerBound = getLowerBound();
+    var higherBound = getHigherBound();
+
+    if(Math.abs(x) >= higherBound || Math.abs(x) < lowerBound && Math.abs(x) !== 0){
+        return x.toExponential();
+    }
+
+    return '' + x;
+};

package.json

+{
+  "name": "ed3-format-default",
+  "version": "0.0.1",
+  "description": "Default format for ed3 library",
+  "main": "index.js",
+  "scripts": {
+    "test": "mocha --compilers js:babel-register"
+  },
+  "keywords": [
+    "format",
+    "excel"
+  ],
+  "author": "missingdays",
+  "license": "ISC",
+  "dependencies": {
+    "d3": "^4.2.0"
+  },
+  "devDependencies": {
+    "babel-preset-es2015": "^6.9.0",
+    "babel-register": "^6.11.6",
+    "expect.js": "^0.3.1",
+    "mocha": "^3.0.0"
+  }
+}

test/test_format.js

+
+import expect from 'expect.js';
+
+import format from '../index';
+
+describe('format', ()=>{
+    it('should use basic format', ()=>{
+        expect(format(0)).to.be('0');
+        expect(format(1)).to.be('1');
+        expect(format(1e-10)).to.be('1e-10');
+        expect(format(1e10)).to.be('1e+10');
+    });
+});