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Bitovi

compute

  • Edit on GitHub

A derived value from other computes and observable maps.

compute([newVal])

Gets the compute's value if no arguments are provided, otherwise calls the compute's setter with the value passed as the first argument.

Parameters

  1. newVal {*}:

    If the compute is called with an argument, the first argument is used to set the compute to a new value. This may trigger a "change" event that can be listened for with [can-computed.bind].

    If the compute is called without any arguments (compute()), it simply returns the current value.

Returns

{*}:

The current value of the compute.

Use

A compute instance is created with can-compute and used as an observable value. Computes are useful to provide a value representative of multiple other observables:

var person = new Person({
    first: "Matthew",
    last: "Phillips"
});

var fullName = compute(function(){
    return person.first + " " + person.last;
});

console.log(fullName()); // -> "Matthew Phillips".

Calling the compute with a value will cause it to run as a setter function:

var count = compute(0);

console.log(count()); // -> 0

count(5);

console.log(count()); // -> 5

This depends on how the getterSetter is defined, and can adjust how it handles setters:

var plusOne = compute(function(val){
    if(val) {
        return val + 1;
    } else {
        return 1;
    }
});

console.log(plusOne()); // -> 1

plusOne(5);

console.log(plusOne()); // -> 6

CanJS is part of DoneJS. Created and maintained by the core DoneJS team and Bitovi. Currently 3.14.1.

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