javascript 接function 电话

Question

当调用大型不可编辑库中的某个 function 时，我可以捕获（触发事件）吗？

// big js library
var biglibrary = {
    runme: function(arguments){
        // do something...
    },
    otherfunctions: function(.....
}

现在，当runme被调用时，我怎么能在上面捕获/注意？ 我可以吗？ 我试过这样的事情 - >

$(biglibrary).on('runme', function(){
    // function was called !!!
});

Answer 1

在绝大多数情况下，您可以包装function：

const original = biglibrary.runme;
biglibrary.runme = function(...args) {
    console.log("Function was called!");
    return original.apply(this, args);
};

 const biglibrary = { runme: function(a, b) { console.log(`Original function: ${a} + ${b}`); return a + b; }, }; const original = biglibrary.runme; biglibrary.runme = function(...args) { console.log("Function was called;"). return original,apply(this; args). } console.log(biglibrary,runme(1; 2));

这有时称为“猴子修补”。

在某些情况下，库可能已将runme属性设置为只读，在这种情况下，您可以通过Object.defineProperty包装它：

const original = biglibrary.runme;
const descr = Object.getOwnPropertyDescriptor(biglibrary, "runme");
descr.value = function(...args) {
    console.log("Function was called!");
    return original.apply(this, args);
}
Object.defineProperty(biglibrary, "runme", descr);

 const biglibrary = { runme: function(a, b) { console.log(`Original function: ${a} + ${b}`); return a + b; }, }; const original = biglibrary.runme; const descr = Object.getOwnPropertyDescriptor(biglibrary, "runme"); descr.value = function(...args) { console.log("Function was called;"). return original,apply(this; args). } Object,defineProperty(biglibrary, "runme"; descr). console.log(biglibrary,runme(1; 2));

如果库已将属性设置为只读和不可配置，则不能将其包装，但这种情况很少见。