Toggling layer lock

app.documents.item(0).layers.itemByName("Layer 1").locked ^= 1;

I hope this helps to you.  and what you expected...

@winterm – If I understand you right you want to un-lock every locked layer and lock every un-locked one?

Then see the following script:

var d= app.documents[0];
var allLayers = d.layers;

var lockedLayersIDsTrue = new Array();
var lockedLayersIDsFalse = new Array();

for(var n=0;n<allLayers.length;n++){
    if(allLayers[n].locked){
        lockedLayersIDsTrue.push(allLayers[n].id);
        }
    else{lockedLayersIDsFalse.push(allLayers[n].id)};
    };

for(var n=0;n<lockedLayersIDsTrue.length;n++){
    allLayers.itemByID(lockedLayersIDsTrue[n]).locked = false;
    };

for(var n=0;n<lockedLayersIDsFalse.length;n++){
    allLayers.itemByID(lockedLayersIDsFalse[n]).locked = true;
    };

First the locked state of every layer (in fact its ID) is recorded in two arrays, one for locked layers, one for unlocked ones.
Then the script goes through the locked layers array and unlocks all recoded layers, after that we visit the locked layers array and lock all recorded layers.

Uwe

^= expression performs a bitwise XOR and assigns the result to the first operand.

Here is a link for full description about XOR.

http://en.wikipedia.org/wiki/XOR_gate

@winterm – forget my version. Imagine's solution is much more smarter:

var d= app.documents[0];

//Toggle: for true set false and vice versa:
for(var n=0;n<d.layers.length;n++){
    d.layers[n].locked ^= 1;
    };

Uwe

Technically it should be

..locked ^= true

because the property 'locked' is a Boolean, not a number. It does work because Javascript internally changes the numbers 0 and Not-0 to boolean false and true (which may or may not be interesting to know, anyway).

The expression a ^= b is shorthand for a = a ^ b. All of the simple math and logical functions can be written that way:

a = a - b -> a -= b

a *= b -> a = a*b

a &= b -> a = a & b

which may seem just to be a programmers' affection at first, but there are actual advantages to it. For example, not only would you have to write out this in full:

app.documents.item(0).layers.itemByName("Layer 1").locked = app.documents.item(0).layers.itemByName("Layer 1").locked ^ true;

but Javascript would have to parse it in its entirety as well. With the singular expression, the left hand part (the a above) is only evaluated once.

The ^ command is a simple Exclusive-Or (a.k.a. XOR), that is one or the other, not neither nor both. If ("Layer 1").locked = false, then

("Layer 1").locked (new) = ("Layer 1").locked=false XOR true

-- the left value (a) is false, the right value (b) is true, so in this case the result is "true", because it is 'true' that 'false XOR true' is "one OR the other". If the layer was locked, it would be

("Layer 1").locked(new) = ("Layer 1").locked=true XOR true

and the expression "true XOR true" equals false because then it is NOT "one OR the other".