reactjs - ES6 arrow function binding and gulp compiling error -

i've been trying hard accomplish code segment below, reading official es6 docs , other blogs:

onhomestorechange = () => (newstate) {     this.setstate(newstate); } 

i used link. seems gulp doesn't job correctly, a semicolon required after class property error after putting 1 this still undefined. here part of gulp file uses transform.

appbundler     // transform es6 , jsx es5 babelify     .transform("babelify", {presets: ["es2015", "stage-0", "react"]})         //.transform(babelify.configure({stage: 0}))     .bundle()     .on('error',gutil.log)     .pipe(source('bundle.js'))     .pipe(gulp.dest(builddestination)); 

i use react 0.14.5 , these dev dependencies.

"babel-preset-es2015": "^6.3.13", "babel-preset-react": "^6.3.13", "babel-preset-stage-0": "^6.3.13", "babelify": "7.2.0", "browserify": "^12.0.1", "gulp": "^3.9.0", "gulp-if": "^2.0.0", "gulp-streamify": "^1.0.2", "gulp-uglify": "^1.5.1", "gulp-util": "^3.0.7", "vinyl-source-stream": "^1.1.0" 

i'm confused , appreciated.

edit - adding react complete code

export default class app extends react.component {   constructor(props) { //put componentwillmount code in constructor     super(props);      //this.bindmethods();     this.state = homestore.getstate();   }    componentdidmount() {     homestore.listen(this.onhomestorechange);   }    componentwillunmount() {     homestore.unlisten(this.onhomestorechange);   }    onhomestorechange = (newstate) => {     //i had syntax error here     this.setstate(newstate);   }    render() {       return (         <div>           components go here         </div>       );   }    bindmethods() {     this.onhomestorechange = this.onhomestorechange.bind(this);   } } 

if use bindmethods() it's working not =>

you have set of brackets. arrow function should take argument in first set of brackets:

onhomestorechange = (newstate) => {     this.setstate(newstate); }; 

the error you're seeing because have defined onhomestorechange () => (newstate), , followed , {...} block.