Ⓒegret.FocusEvent 用法

透過 FocusEvent 製作 placeholder 效果

let placeholder = '請輸入一段話:';
let tf = new egret.TextField();
tf.type = egret.TextFieldType.INPUT;
tf.inputType = egret.TextFieldInputType.TEXT;
tf.textColor = 0xb2b2b2;
tf.size = 32;
tf.width = 500;
tf.height = 90;
tf.textAlign = egret.HorizontalAlign.LEFT;
tf.verticalAlign = egret.VerticalAlign.MIDDLE;
tf.border = true;
tf.text = placeholder;
this.addChild(tf);
tf.addEventListener(egret.FocusEvent.FOCUS_IN, () => tf.text === placeholder && (tf.text = ''), this);
tf.addEventListener(egret.FocusEvent.FOCUS_OUT, () => tf.text === '' && (tf.text = placeholder), this);