function(){}; do?

 

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  • Javascript || operator 5 answers
  • Is there a better way to do optional function parameters in JavaScript? [duplicate] 29 answers

    • In words: 

    if there is no processMethod, create it empty.

    || works with booleans, so it checks if the first operand processMethod has a boolean-equivalent. If processMethod is defined and not null, the boolean-equivalent is true . If processMethod is undefined or null, the boolean-equivalent is false . In the false-case, || looks for a boolean-equivalent of the second-operand, its not null so its boolean-equivalent is true .

    false || true false || true resolves to true so processMethod becomes function(){} .

    Btw function(){} is a empty function whom used to not throw a error on processMethod()

    It essentially checks whether it exists or not. If it doesn't exist, assign it. 

    function doSomething(o) {
    o = o || {};
}

    In the above case, it checks whether a value for o was passed. If not it assigns an empty object to it.

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