jQuery VS Javascript

It's all about performance and development speed.

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jQuery :
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1. jQuery is library or you can say that its built on javascript
2. Jquery is need to be access through jquery patch latest patch is 1.5
3. Another advantage of jquery is that its less your code rather than using javascript.
4. In complex situation Jquery will be more helpfull due to less code written and easily manageable

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JavaScript : 

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1. Javascript is client language for which you dont need any requirement.
2. It is incredibly useful and overused, but that if you really need it, a framework is the way to go.
3. Javascript is the source, the actual scripts that browser responds to.