Flatten a javascript object to pass as querystring

Question

I have a javascript object that I need to flatten into a string so that I can pass as querystring, how would I do that? i.e:

{ cost: 12345, insertBy: 'testUser' } would become cost=12345&insertBy=testUser

I can't use jQuery AJAX call for this call, I know we can use that and pass the object in as data but not in this case. Using jQuery to flatten to object would be okay though.

Thank you.

Answer 1

You want jQuery.param:

var str = $.param({ cost: 12345, insertBy: 'testUser' });
// "cost=12345&insertBy=testUser"

Note that this is the function used internally by jQuery to serialize objects passed as the data argument.

Answer 2

Here's a non-jQuery version:

function toQueryString(obj) {
    var parts = [];
    for (var i in obj) {
        if (obj.hasOwnProperty(i)) {
            parts.push(encodeURIComponent(i) + "=" + encodeURIComponent(obj[i]));
        }
    }
    return parts.join("&");
}

Answer 3

My ES6 version (pure Javascript, no jQuery):

function toQueryString(paramsObject) {
  return Object
    .keys(paramsObject)
    .map(key => `${encodeURIComponent(key)}=${encodeURIComponent(paramsObject[key])}`)
    .join('&')
  ;
}

Answer 4

Here is another non-jQuery version that utilizes lodash or underscore if you're already using one of those libraries:

var toQueryString = function(obj) {
  return _.map(obj,function(v,k){
    return encodeURIComponent(k) + '=' + encodeURIComponent(v);
  }).join('&');
};

Answer 5

Try the $.param() method:

var result = $.param({ cost: 12345, insertBy: 'testUser' });

Answer 6

This is an old question, but at the top of Google searches, so I'm adding this for completeness.

If 1) you don't want to user jQuery, but 2) you want to covert a nested object to a query string, then (building off of Tim Down and Guy's answers), use this:

function toQueryString(obj, urlEncode) {
    //
    // Helper function that flattens an object, retaining key structer as a path array:
    //
    // Input: { prop1: 'x', prop2: { y: 1, z: 2 } }
    // Example output: [
    //     { path: [ 'prop1' ],      val: 'x' },
    //     { path: [ 'prop2', 'y' ], val: '1' },
    //     { path: [ 'prop2', 'z' ], val: '2' }
    // ]
    //
    function flattenObj(x, path) {
        var result = [];

        path = path || [];
        Object.keys(x).forEach(function (key) {
            if (!x.hasOwnProperty(key)) return;

            var newPath = path.slice();
            newPath.push(key);

            var vals = [];
            if (typeof x[key] == 'object') {
                vals = flattenObj(x[key], newPath);
            } else {
                vals.push({ path: newPath, val: x[key] });
            }
            vals.forEach(function (obj) {
                return result.push(obj);
            });
        });

        return result;
    } // flattenObj

    // start with  flattening `obj`
    var parts = flattenObj(obj); // [ { path: [ ...parts ], val: ... }, ... ]

    // convert to array notation:
    parts = parts.map(function (varInfo) {
        if (varInfo.path.length == 1) varInfo.path = varInfo.path[0];else {
            var first = varInfo.path[0];
            var rest = varInfo.path.slice(1);
            varInfo.path = first + '[' + rest.join('][') + ']';
        }
        return varInfo;
    }); // parts.map

    // join the parts to a query-string url-component
    var queryString = parts.map(function (varInfo) {
        return varInfo.path + '=' + varInfo.val;
    }).join('&');
    if (urlEncode) return encodeURIComponent(queryString);else return queryString;
}

Use like:

console.log(toQueryString({
    prop1: 'x',
    prop2: {
        y: 1,
        z: 2
    }
}, false));

Which outputs:

prop1=x&prop2[y]=1&prop2[z]=2

Answer 7

General JavaScript:

function toParam(obj) {
  var str = "";
  var seperator = "";
  for (key in obj) {
    str += seperator;
    str += enncodeURIComponent(key) + "=" + encodeURIComponent(obj[key]);
    seperator = "&";
  }
  return str;
}


toParam({ cost: 12345, insertBy: 'testUser' })
"cost=12345&insertBy=testUser"

Answer 8

Another version:

function toQueryString(obj) {
    return Object.keys(obj).map(k => {
      return encodeURIComponent(k) + "=" + encodeURIComponent(obj[k])
    })
    .join("&");
}

Answer 9

var myObj = { cost: 12345, insertBy: 'testUser' },
    param = '',
    url   = 'http://mysite.com/mypage.php';    

for (var p in myObj) {
  if (myObj.hasOwnProperty(p)) {
    param += encodeURIComponent(p) + "=" + encodeURIComponent(myObj[p]) + "&";
  }
}

window.location.href = url + "?" + param;

Answer 10

you can use this

function serialize(obj)
{
    let str = []

    for(var p in obj)
    {
      if(obj.hasOwnProperty(p)) str.push(encodeURIComponent(p) + '=' + encodeURIComponent(obj[p]))
    }

    return str.join('&')
}

try on JSFiddle on this link https://jsfiddle.net/yussan/kwmnkca6/

Answer 11

ES6 version of Jrop's answer (also parses nested params)

const toQueryString = (obj, urlEncode = false) => {
  if (!obj) return null;
  const flattenObj = (x, path = []) => {
    const result = [];
    Object.keys(x).forEach((key) => {
      if (!Object.prototype.hasOwnProperty.call(x, key)) return;
      const newPath = path.slice();
      newPath.push(key);
      let vals = [];
      if (typeof x[key] === 'object') {
        vals = flattenObj(x[key], newPath);
      } else {
        vals.push({ path: newPath, val: x[key] });
      }
      vals.forEach((v) => {
        return result.push(v);
      });
    });
    return result;
  };

  let parts = flattenObj(obj);
  parts = parts.map((varInfo) => {
    if (varInfo.path.length === 1) {
      varInfo.path = varInfo.path[0]; // eslint-disable-line no-param-reassign
    } else {
      const first = varInfo.path[0];
      const rest = varInfo.path.slice(1);
      varInfo.path = `${first}[${rest.join('][')}]`; // eslint-disable-line no-param-reassign
    }
    return varInfo;
  });

  const queryString = parts.map((varInfo) => {
    return `${varInfo.path}=${varInfo.val}`;
  }).join('&');
  if (urlEncode) {
    return encodeURIComponent(queryString);
  }
  return queryString;
};