[英]How to detect a change in a variable when everytime its value is changed in angular
I would like to detect the change in variable which is of type int everytime the value is changed based on that i have do few operations to be performed .我想检测每次更改值时类型为 int 的变量的更改,因为我执行的操作很少。
The variable is int value which changes on button click.变量是 int 值,它会在单击按钮时发生变化。
I have tried it using @Input which is totally doesn't suit my requirement.我已经尝试过使用 @Input 这完全不符合我的要求。
addWhereCondition() {
++this.numberOfWhereConditions;
}
deleteWhereCondition() {
if (this.numberOfWhereConditions > 1) {
--this.numberOfWhereConditions;
} else {
this.numberOfWhereConditions = 1;
}
}
numberOfWhereConditions is the variable which is changed and need to detect that change numberOfWhereConditions 是已更改且需要检测该更改的变量
You can create a getter and setter for it.您可以为它创建一个 getter 和 setter。 Before the constructor...
在构造函数之前...
private _numberOfWhereConditions: number;
get numberOfWhereConditions(): number {
return this._numberOfWhereConditions
}
set numberOfWhereConditions(newNum: number) {
if (this._numberOfWhereConditions !== newNum) { // if the new number is not the same as the old number
// Logic for what happens when there is a change detected
this._numberOfWhereConditions = newNum; // You do need to explicitly set the new number
}
Within the HTML, you would call numberOfWhereConditions
and within the typescript, you would call this.numberOfWhereConditions
.在 HTML 中,您将调用
numberOfWhereConditions
而在打字稿中,您将调用this.numberOfWhereConditions
。
Here's a tutorial article .这是一篇教程文章。
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