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p5.js | httpPost() Function

  • Last Updated : 27 Apr, 2020

The httpPost() function in p5.js is used to execute an HTTP POST request. The datatype returned is automatically guessed by p5 based on the URL, when it is not specified.

The data returned could be loaded in the preload() function so that it can be accessed immediately in the program.

Syntax:

httpPost( path, [datatype], [data], [callback], [errorCallback] )

OR

httpPost( path, data, [callback], [errorCallback] )

OR



httpPost( path, callback, [errorCallback] )

Parameters: This function accept five parameters as mentioned above and described below:

  • path: It is a string that denotes the path of the URL or file to load.
  • datatype: It is a string that specifies the type of data that will be recieved. It can have the values of “json”, “jsonp”, “xml”, or “text”. It will default to ‘text’ is no parameter is specified. It is an optional parameter.
  • data: It is an Object or a Boolean value that specifies the parameter data passed with the request.
  • callback: It is a function which is called when this function executes successfully. The first argument for this function is the data returned from the API. It is an optional parameter.
  • errorCallback: It is a function which is called if there is any error in executing the function. The first argument for this function is the error response. It is an optional parameter.

Return Value: It returns a promise that can be resolved with the data when the operation completes successfully, or be rejected when an error takes place.

Below examples illustrates the httpPost() function in p5.js:

Example 1:




function setup() {
  createCanvas(550, 200);
  textSize(18);
   
  text("Click on the button below"+
       " to send a POST request.", 20, 40);
   
  postBtn = createButton("Post Request");
  postBtn.position(30, 60);
  postBtn.mouseClicked(postRequest);
}
   
function postRequest() {
   
  // Do a POST request to the test API
  let api_url = 'https://reqres.in/api/users';
   
  // Example POST data
  let postData = { id: 1, name: "Sam",
                  email: "sam@samcorp.com" };
   
  httpPost(api_url, 'json', postData, function (response) {
    text("Data returned from API", 20, 100);
   
    text("The ID in the data is: "
         + response.id, 20, 140);
    text("The Name in the data is: " 
         + response.name, 20, 160);
    text("The Email in the data is: " 
         + response.email, 20, 180);
  });
}

Output:
post-request-btn

Example 2:




function setup() {
  createCanvas(550, 200);
  textSize(18);
   
  // Do a POST request to the test API
  let api_url = 
   
  let postData = { id: 1, name: "James"
                  email: "james@james.j.com" };
   
  httpPost(api_url, 'json', postData, 
           onSuccessfulFetch, onErrorFetch);
}
   
function onSuccessfulFetch(response) {
  text("Data returned from API", 20, 60);
   
  text("The ID in the data is: " 
       + response.id, 20, 100);
  text("The Name in the data is: "
       + response.name, 20, 120);
  text("The Email in the data is: " 
       + response.email, 20, 140);
}
   
function onErrorFetch() {
  text("There was an error doing"+
       " the request.", 20, 60);
}

Output:

Online editor: https://editor.p5js.org/

Environment Setup: https://www.geeksforgeeks.org/p5-js-soundfile-object-installation-and-methods/

Reference: https://p5js.org/reference/#/p5/httpPost




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