my.offMemoryWarning

// Remove all memory warning listeners
my.offMemoryWarning();

Page({
  onLoad() {
    my.onMemoryWarning(this.handleMemoryWarning);
  },

  handleMemoryWarning(res) {
    console.log('Memory warning:', res.level);
    this.releaseResources();
  },

  onUnload() {
    my.offMemoryWarning(this.handleMemoryWarning);
  },

  releaseResources() {
    this.setData({ cachedImages: [] });
  }
});

Page({
  data: {
    monitoringMemory: false
  },

  startMemoryMonitoring() {
    my.onMemoryWarning(this.onMemoryWarning);
    this.setData({ monitoringMemory: true });
  },

  stopMemoryMonitoring() {
    my.offMemoryWarning(this.onMemoryWarning);
    this.setData({ monitoringMemory: false });
  },

  onMemoryWarning(res) {
    console.log('Memory level:', res.level);
  }
});