JavaScript 最讓我驚訝的部分是它周圍總是有新事物發(fā)生。 而且，無論您對它了解多少，您都將始終了解有關(guān)它的新事物。
這些問題我收集了很長時間。 在大多數(shù)問題中，我真的不知道輸出會是什么，直到我自己嘗試了它們。
所以在這里我將它們記錄下來，以便其他人可以利用它來學(xué)習(xí)新概念：
輸出：
21{name: “Lydia”} // age won’t be included. Because property defined with defineProperty are non enumerable by default.
輸出：
false // delete operator only deletes a key in objecttrue // when we don’t use any declaration before any variable, it will be treated as a global variable, and will be added as deletable entity in window object.undefined
輸出：
[ { name: “Noren Red”} ] Initially I thought it will log [ null ] because we have initialised person with nullBut in reality, we are only setting new reference to person variable. Previous reference will be used in members arrayIn Short, { name: “Noren Red”} lives in some memory space whose address is X201and this is how referencing is workinglet person = X201const members = [ X201 ]person = null
輸出：
Silver Surfer Because when we return a property, the value of the property is equal to the returned value, not the value set in the constructor function.
輸出：
With the padStart method, we can add padding to the beginning of a string. The value passed to this method is the total length of the string together with the padding. The string “Silver Surfer” has a length of 13. name.padStart(14) inserts 1 space at the start of the string, because 13 + 1 is 13. If the argument passed to the padStart method is smaller than the length of the array, no padding will be added.
輸出：
777If we pass string and number combination to parseInt, what parseInt does is, it check at which position wrong datatype is getting started, if value before the wrong datatype is a valid number, it will return the valid number.
輸出：
1 2 and undefined 3 and undefined 4 If we don’t pass initial value, then by default x will be first value of array, and y will be second value of array.
輸出：
one – [“”, ” is “, ” years old”]two – Thorthree – 1000one – [“hey there, are you amazed”]two – undefinedthree – undefinedIf we use tagged template literals, the value of the first argument is always an array of the string values.The remaining arguments get the values of the passed expressions!
輸出：
1undefined2
輸出：
function // Classes in JS are functions under the hood
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