Is it worth buying a portable iPhone charger?

Hi, I want to buy a portable charger, and I want to know the functions of one. How long do portable chargers charge a phone before going dead? How do you charge a portable charger? How well do these chargers work? Which is better: a portable iphone charger or a wall charger?

Added (1). Also, can you still charge it if there's no electricity?

I dropped my iPhone 6 in milk

I dropped my iPhone 6 in milk I couldn't cut it off and after a while it cut off by it self and the screen was in slow motion and messed up and It turned purple so after it cut off by its self I left in in rice and for like a couple minutes now please help me

Camera and light not working after dropping iphone 4 in the toilet?

Okay so I dropped my phone in the toilet and got it right back out, it is still working except it's stuck on headphone mode and the camera and flashlight are not working, they have what looks to be little water droplets on the inside and I don't know how to fix it!

Is this paypal seller lying to me?

Recently, I was scammed into paying for someone's item for them, thinking i was buying an iphone 6. I spoke to the seller and they agreed that they would send the money back when i close the dispute. The amount was £170.10 but they claimed that only 136 pounds was deposited back into their account and that is what they sent me. Were they lying to me as I'm trying to think of what to do next.

God Puts Me In The Worst Situation and around bad people?

At school i usually get teased and bullied and the person i love doesn't even love me back i'm only 15 but my life seems like trash i hate my life at home! All of my friend have great lifes and get anything they want! But my mom smashes my iPhone 6 and won't buy me another phone! I'm not spoiled at all i hate when people say that.