CODEWITHSUNDEEP
javascriptfunctionloops
Jellicle
Jellicle

Reputation: 30236

Defining functions in a Javascript loop and using variables set in the loop

I'm trying to define functions in a loop in javascript...

for (var i in myArray) {
  Object.defineProperty(object, "field"+i, { ... });
}

...and each function needs to make use of a variable which is set in that loop...

for (var i in myArray) {
  Object.defineProperty(object, "field"+i, { 
    get: function() { return "some operation" + myArray[i]; }
  });
}

...but this doesn't work because when I call the functions (long after they're defined), i evaluates to the last item in the myArray. All of the functions I defined in the loop return the same (erroneous) value.

Can anyone tell me how to accomplish my aim: make use of myArray[i] within my getter function?

Upvotes: 0

Views: 57

Answers (2)

Jellicle
Jellicle

Reputation: 30236

I created an extra closure by using a factory function:

function makeGetter(myString) {
  return function () { return "some operation" + myString; };
}
for (var i in myArray) {
  Object.defineProperty(object, "field"+i, { 
    get: makeGetter(myArray[i])
  });
}

Upvotes: 1

user3299259
user3299259

Reputation:

this could be done as following

for (var i in myArray) 
  {
  var getter=function yourName () { return "some operation" + yourName.data;}
  getter.data=myArray[i];
  Object.defineProperty(object, "field"+i, { 
  get: getter});
  }

you can define a function with

 var test=function testit () {}

testit can be use to call the function from inside the function. its a locale variable inside, its replacing arguments.callee which is depreacted in strict mode.

test is defined outside the function to call it from outside

Upvotes: 0

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