Execute a function from object value in javascript

Question

I am trying to execute a function from each object key here is the code.

var testObj = { text: "this is text" , alltext: "this is all text" };

function text() {
    alert("this is test function for first value");
}

function alltext() {
    alert("this is test function for first second!");
}

for (item in testObj) { 
    console.log(item);
    item();
}

This gives me that item not a function.

Please visit this link to see the original code. I am using Backbone.js to create a form.The code is commented.

http://vianx.com/tst/script2.js

in this case gives that the "fieldConstructor" in not a function.

Only solution in your case, without assigning those functions as members of an object... is eval. — Kyll
– Kyll, Commented Feb 9, 2016 at 21:06
Put your funcs in an object like var funcs = {text:function(){},alltext:function(){}}; then do funcs[item]() — MDEV
– MDEV, Commented Feb 9, 2016 at 21:43

Heretic Monkey · Accepted Answer · 2021-02-16 14:23:50Z

0

So I believe you are mistaken about how a dictionary works in javascript. The first value is a key and will always be a string value to do what you want you can do this

var testObj = [[text, "this is text"] , [alltext, " thi is all text" ]];

function text () {
  alert( "this is test function for first value");
}

function alltext () {
  alert( "this is test function for first second!" );
}


for ( index in testObj ) {
   
  console.log(index);
  testObj[index][0]();
}

edited Feb 16, 2021 at 14:23

Heretic Monkey

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answered Feb 9, 2016 at 21:09

Nicholas Mata

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2 Comments

codeforce Over a year ago

I have used the underscore "pair" object method to convert the object into array "key,value" pairs.Then I can execute them. _.pairs({one: 1, two: 2, three: 3}); => [["one", 1], ["two", 2], ["three", 3]]

Nina Scholz Over a year ago

@Jack Mata, please do not indent the tags for code snippets (just the tags). it makes funny renderings.

Alessio Cantarella · Accepted Answer · 2016-02-09 21:09:48Z

0

You should use JavaScript eval function:

for (item in testObj) {
    console.log(testObj[item]);
    eval(item + "()");
}

answered Feb 9, 2016 at 21:09

Alessio Cantarella

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3 Comments

codeforce Over a year ago

Is there is anyway to avoid eval ?? Because it has a security risk?

Alessio Cantarella Over a year ago

It depends… A malicious user is potentially able to execute any client-side script he wants with his browser's Developer Tools. Remember that these scripts will be running on his client, not on your server. To learn more, read this: stackoverflow.com/questions/1651118/…

Barmar Over a year ago

@codeforce It's only a security risk if the contents of testObj can be manipulated outside the control of the user.

Matt · Accepted Answer · 2016-02-09 21:11:31Z

0

Or you could reference the functions from within your object

var testObj = { text: text , alltext : alltext };

function text() {
  alert( "this is test function for first value");
}

function alltext() {
  alert( "this is test function for first second!" );
}


for ( item in testObj ) {

  console.log(item);
  testObj[item]();
}

answered Feb 9, 2016 at 21:11

Matt

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1 Comment

codeforce Over a year ago

I can not because I have a data from outside source as key value pairs.

Veenkar · Accepted Answer · 2016-02-09 21:12:18Z

0

Construct testObj is like this:

var testObj = { 
    text: function(){alert("this is test function for first value")} ,
    alltext : function(){alert("this is test function for first second!")} 
};

Then simply call testObj.a();

answered Feb 9, 2016 at 21:12

Veenkar

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4 Comments

Barmar Over a year ago

You mean testObj[item]. You have to use [] notation to access an object property dynamically.

Barmar Over a year ago

No, that will look for a property literally named item, not use the value of the item variable.

Veenkar Over a year ago

I would argue. They are quite the same, except that the square bracket operator can access object's members using a string variable, whereas dot operator can only use literals. Please, take a look at: /questions/4968406/javascript-property-access-dot-notation-vs-brackets

Barmar Over a year ago

That's exactly what I'm saying. testObj.a() looks for a literal property named a, it doesn't use the value of the variable a. If the property name is in a string variable, you have to use square brackets.

jsxsl · Accepted Answer · 2016-02-09 21:40:23Z

You can do it by attaching the dynamic functions to the window object.

var testObj = { text: "this is text", alltext: " thi is all text" };

for (var item in testObj) {
    window[item] = function () {alert("hello world")};
}

console.log(window['text'],window['alltext']);

window.text();
window.alltext();

The functions can also be called without using "window." i.e.:

text();
alltext();

Or if you are wanting to call a function by property name dynamically...

var testObj = { text: "this is text", alltext: " thi is all text" };

window['text'] = function() {
    alert("this is test function for first value");
}

window['alltext']  = function (){
    alert("this is test function for first second!");
}

for (var item in testObj) {
    window[item]();// = function () {alert("hello world")};
}

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