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?

• sg.cc: What line is erroring out?
• user1106925: 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.

Answer 1

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)

• elclanrs: Indeed, I'd rewrite that properly.
• elclanrs: @wintercounter: eslint can help you catch those ASI errors.
• wintercounter: I have but didn't throw any warning in PhpStorm.