After Effects Expressions

After Effects expressions are little pieces of code that can change values in a more automated way. The typebox to write the expressions is accessed by alt-clicking the stopwatch icon of a value.

linear animation of value
time*a The resulting value will be a times the change in seconds.

loop keyframes
loopOut("cycle",0)

Pre and Post infinity
To continue a curve along its path so the motion goes on beyond your keyframes you can use the following expressions. Both: if (time-key(1).time<=0) {loopIn(type = "continue")} else loopOut(type = "continue") Pre: loopIn(type=”continue”); Post: loopOut(type=”continue”);

wiggle
This will make a value variate. Like a noise sinus. wiggle(a,b) a=times per second b=amplitude If you just want the effect on one of multiple values you can use the following expression: [value[0],wiggle(a,b)[1]] value=the original value [0]=frist float [1]=second float

timer
Have a text layer with counting numbers: (a.value.toFixed(b)+"c") a= tipically being pickwhipped to a slider control b=number of decimal places c=optional string of text behind it

scrolling text
You can make a scrolling text with a text layer and animating the scale (it won't work with opacity) with a range selector. To have the last revealed line static instead of the first one put the following expression on the position of the text layer: pLine=sourceRectAtTime(time).height; scaler=transform.scale[1]/100; value-[0,pLine*scaler]