Unexpected token s in JSON at position 0 at JSON.parse

when i call php rest api using http post in ionic 3 my code throw an error

"SyntaxError: Unexpected token s in JSON at position 0
** at JSON.parse ()**
** at XMLHttpRequest.onLoad (http://localhost:8100/build/vendor.js:74945:51)**
** at t.invokeTask (http://localhost:8100/build/polyfills.js:3:15660)**
** at Object.onInvokeTask (http://localhost:8100/build/vendor.js:5125:33)**
** at t.invokeTask (http://localhost:8100/build/polyfills.js:3:15581)**
** at r.runTask (http://localhost:8100/build/polyfills.js:3:10834)**
** at e.invokeTask [as invoke] (http://localhost:8100/build/polyfills.js:3:16794)**
** at p (http://localhost:8100/build/polyfills.js:2:27648)**
** at XMLHttpRequest.v (http://localhost:8100/build/polyfills.js:2:27893)"**

here is my code


    let orddata = {"userid":this.userid};
    let sendData = {
      "orderdata": orddata,
      "orderdetail": this.cartpageitemdata

    // this.senddata.push("orderdata",ord);
    // this.senddata.push("orderdetail",this.cartpageitemdata);

    this.service.post("http://localhost/smartvege/adminpanel/API/addorder.php?access_tocken=ae189b0987d4abc138197a175b488db5",sendData).then(data => {

    // console.log(sendData);


It’s pretty unusual for an Ionic app to be making REST requests to localhost, because localhost is the device the Ionic app is running on. That being said, the error message is telling you that it’s expecting JSON, but you’re feeding it not-JSON that starts with an ‘s’. Attaching to the app with a debugger and watching the network requests should tell you what comes after that ‘s’ and help you further isolate the actor that is returning not-JSON.