如何在javascript对象的元素中将值设置为函数？

Question

I have this code:

this.mGroupFunctions={};
        for(var i=0; i<cols.length; i++){
            var col=cols[i];
            this.mGroupFunctions[col]=function(oContext) {
                var name = oContext.getProperty(col);
                return {
                  key: name,
                  text: name
                };
              };
        }

If I debug it i obtain

where into a function I insert col and not the value of variable col!!!

How can I resolve my problem??

Answer 1

When the function runs, the variable col no longer contains the value that it had when the function was created. You can use an immediately invoked function expression (IIFE) to create a closure that captures the value of col for each iteration in the loop:

this.mGroupFunctions = {};
for(var i=0; i<cols.length; i++){      

  this.mGroupFunctions[cols[i]] = (function(col){

    return function(oContext) {
      var name = oContext.getProperty(col);
      return {
        key: name,
        text: name
      };
    };

  })(cols[i]);

}