[英]Closure with parameter in Javascript
這是一個簡單的問題,為什么 var1 和 var2 undefined 。
我試圖在 javascript 中學習閉包並添加了一個參數,但不確定為什么它是未定義的。
var closureFunction = function(var1,var2){
var privateVar = var1+var2;
console.log("Sum of "+ var1 +" and "+ var2+"");
return function(){return privateVar;}
}();
console.log(closureFunction(2,3));
當您在函數后使用方括號 () 時,它會立即執行。 在這種情況下,您沒有在那里傳遞任何參數。
它可以有兩種方式。
var closureFunction = function(var1,var2){
var privateVar = var1+var2;
console.log("Sum of "+ var1 +" and "+ var2+"");
return function(){return privateVar;}
}(2,3); //prints 'Sum of 2 and 3'
console.log(closureFunction()); //prints '5'
或者你可以分步傳遞參數
var closureFunction = function(var1){
return function(var2 ){
console.log("Sum of "+ var1 +" and "+ var2+"");
return var1 + var2;
}
}(2); //just return a 'closure' function
console.log(closureFunction(3)); //prints 'Sum of 2 and 3 5'
或者您可以稍后執行。
var closureFunction = function(var1){
return function(var2 ){
console.log("Sum of "+ var1 +" and "+ var2+"");
return var1 + var2;
}
};
var x = closureFunction(2); //return a 'closure' function
console.log(x(3)); //prints 'Sum of 2 and 3 5'
一旦可用,您必須調用閉包。
var closureFunction = function(var1, var2) { var privateVar = var1 + var2; console.log("Sum of " + var1 + " and " + var2 + ""); return function() { return privateVar; } }; console.log(closureFunction(2, 3)());
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