How to convert my fat arrow function to a "normal" function in javascript

Question

I'm just trying to convert this to a normal js function without the "fat arrow".

I want body => to be a normal function.

How do I write that?

snippet from code

fetch(this.JobExecEndpoint)
  .then(response => response.json())
  .then(body => {
    this.cleanStartTime = moment(body[0].time_start);
    this.cleanEndTime = moment(body[0].time_end);
    this.cleanDuration = this.calculateDuration(
      this.cleanStartTime,
      this.cleanEndTime
    );

How do you think you might do it? Have you tried anything? Also, your example code is missing a closing bracket and parenthesis. — Herohtar, Jul 01 '19 at 20:27
@SergeyDenisov I believe the fat arrow function might be causing the issue that I posted here https://stackoverflow.com/questions/56840300/why-am-i-getting-property-of-undefined-in-this-vue-js-example/56840535#56840535 — benjaminadon, Jul 01 '19 at 20:30
browsers that don't support arrow functions (IE) also don't support fetch, so polyfill might be needed for it — Slai, Jul 01 '19 at 21:51
Possible duplicate of [What's the meaning of "=>" (an arrow formed from equals & greater than) in JavaScript?](https://stackoverflow.com/questions/24900875/whats-the-meaning-of-an-arrow-formed-from-equals-greater-than-in-javas) — Makyen, Jul 02 '19 at 02:27

score 0 · Accepted Answer · answered Jul 01 '19 at 20:31

0

// Hold a reference to "this" object inside a variable else you won't be able to access it using the "this" inside the callback function

var that = this; 

fetch(this.JobExecEndpoint).then(function(response)
{
     return response.json();
})
.then(function(body)
{
    that.cleanStartTime = moment(body[0].time_start);
    that.cleanEndTime   = moment(body[0].time_end);
    that.cleanDuration  = that.calculateDuration (
        that.cleanStartTime,
        that.cleanEndTime
    );
});

I hope this helps, let me know if you have any question :)

answered Jul 01 '19 at 20:31

Zahid Saeed

152
2
9

What's the point of `var that = this` when you can just do `function(body){}.bind(this)`? – meyi Jul 01 '19 at 20:34
You can do that as well. The syntax will just change a little bit. That's total up to you. If you use this method then you will need to use `.bind(this)` on each of the `.then()` function where was `var that = this` relieves you from this problem and you can continue chaining as long as you like :) – Zahid Saeed Jul 01 '19 at 20:36
@meyi Using `bind()` ends up being considerably slower execution. At least it did the last time I ran a performance test on it; it could have changed. Thus, if you can avoid using `.bind()` (without significant inconvenience), it's better to just use a variable. – Makyen Jul 02 '19 at 02:20

How to convert my fat arrow function to a "normal" function in javascript

1 Answers1