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I can`t get why in my function not changing value of variable. Here my code.
var count = function(datain){
let temparr = [],
countobj = {};
$.each(datain, function(key, val) {
console.log(temparr);
countobj.cost = +$(val).find("[name]").text();
console.log(countobj);
temparr.push(countobj);
console.log(temparr);
});
console.log(temparr);
return temparr;
};
let countarr = count(datain);
console.log(countarr);
This function part of function that fires on ajax success, ajax i call on some select changes. Datain - result of ajax. At first time call this function work`s fine, but all another fires returns me first time set countarr. All data in key, val - correct, but i cant understand why "countarr" returns me result of first call and not re-set temparr inside function. Thanks for reply!
335
JavaScript variables declare outside or inside loop? The ECMA-/Javascript language hoists any variable which is declared with var anywhere to the top of a function. That is because this language does have function scope and does not have block scope like many other C-like languages.
For example, processing a response after an HTTP request is completed or after some other processing is done. So what happens then, is that the doSthWithCallbacks (general expression for all JavaScript function that use a callback) schedules the callback function to be executed at a later stage. But the for loop isn't just scheduling one callback.
I thought it wasn't wise to declare variables within a loop. It's not. Another unwise thing is reassigning a const. Show activity on this post.
var answer = 'Yes I am!'; Creating a variable in JavaScript is called "declaring" a variable. You declare a JavaScript variable with the var keyword: After the declaration, the variable has no value (technically it has the value of undefined ). To assign a value to the variable, use the equal sign:
You're reusing the same countobj object on each loop, pushing a reference to that single object repeatedly into the array.
You need to create a new object on each loop:
var count = function(datain) {
let temparr = [],
countobj; // ***
$.each(datain, function(key, val) {
countobj = {}; // ***
console.log(temparr);
countobj.cost = +$(val).find("[name]").text();
console.log(countobj);
temparr.push(countobj);
console.log(temparr);
});
console.log(temparr);
return temparr;
};
let countarr = count(datain);
console.log(countarr);
As there's just the one property, you don't need a variable. Here's that same code without the variable and with the console.log lines removed:
var count = function(datain) {
let temparr = [];
$.each(datain, function(key, val) {
temparr.push({cost: +$(val).find("[name]").text()});
});
return temparr;
};
let countarr = count(datain);
console.log(countarr);
Or you could even use map; and since you're using ES2015+ (I can tell from let), we can use an arrow function:
let count = function(datain) {
return datain.map(val => ({cost: +$(val).find("[name]").text()}));
};
let countarr = count(datain);
console.log(countarr);
If datain is only array-like, not an actual array, use Array.from instead of map:
let count = function(datain) {
return Array.from(datain, val => ({cost: +$(val).find("[name]").text()}));
};
let countarr = count(datain);
console.log(countarr);
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