I have told you this is literally “I have told you these things” see 14.25). It is difficult to define precisely what is referred to by this, though it certainly includes more than what is said in verse 10. It includes at least verse 9 and perhaps all of verses 7-8 as well. I have told you this may be rendered “I have told you all this” in order to indicate that the reference is not limited to the immediately preceding words.

My joy (used of Jesus) refers to the joy that grows out of absolute obedience to the Father and the perfect unity of love they share with each other. So that my joy may be in you may be rendered in some languages “so that you will have the same kind of joy that I have.” Joy may be expressed idiomatically in some languages as “dance within the heart” or “to have a happy heart.”

Joy may be complete is a favorite Johannine expression (note John 3.29; 1 John 1.4; 2 John 12). The completeness of joy may be expressed in some languages as “and so that you may be completely joyful” or “… completely happy.” In some languages, however, completeness is expressed as a negative of lacking, for example, “so that there may be nothing lacking in your joy” or “so that your joy may have nothing missing.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .