Existing function "is not a function"

Question

Check the console with this JSFiddle which says the following in Chrome:

Uncaught TypeError: handlerHelper(...) is not a function

"use strict" function parseRoute(route, Handlers){ let parsed = Handlers route.split('->').forEach(function(s){ parsed.hasOwnProperty(s) && (parsed = parsed[s]) }) return parsed } function handlerHelper(Handlers, ev){ let parsed = parseRoute(ev.name, Handlers) applyHandlers(parsed, ev) } function applyHandlers(obj, ev){ for (let i in obj) { if (obj.hasOwnProperty(i)){ console.log(handlerHelper, typeof handlerHelper) typeof obj[i] === 'object' && handlerHelper(obj[i], ev) (i = obj.handlers) && i.length && i.forEach(function(fn){ fn.apply(null, ev) }) } } } handlerHelper({ $: { handlers: [function(){}] } }, { name: '$->Test' })

On the console it clearly says it is function. This is a recursive function and it throws only after in the 3rd iteration. Really weird. Any clues about what's the problem?

If you're going to elide semicolons like some of us do, you should consider adopting a set of practices where you never start a line with a binary or unary postfix operator without including a leading ;. Also, I'd personally avoid using the return value of an assignment as a logical condition like you're doing, as well as logical operators for flow control. Let your minifier handle that. — user1106925
– user1106925, Commented Jan 30, 2016 at 18:29

elclanrs · Accepted Answer · 2016-01-30 18:13:57Z

5

The lack of semicolons is the issue:

 && handlerHelper(obj[i], ev) (i = obj.handlers)

This is the same as:

 && handlerHelper(obj[i], ev)(i = obj.handlers)

And handlerHelper does not return a function, thus the error. You need a semicolon there:

 && handlerHelper(obj[i], ev) ;(i = obj.handlers)

answered Jan 30, 2016 at 18:13

elclanrs

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3 Comments

elclanrs Over a year ago

Indeed, I'd rewrite that properly.

elclanrs Over a year ago

@wintercounter: eslint can help you catch those ASI errors.

wintercounter Over a year ago

I have but didn't throw any warning in PhpStorm.

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