62 lines
1.4 KiB
JavaScript
62 lines
1.4 KiB
JavaScript
const EventEmitter = require('events');
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// Note: as of now only supports trailing the price going up (after
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// a buy), on trigger (when the price moves down) you should sell.
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// @param initialPrice: initial price, preferably buy price
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// @param trail: fixed offset from the price
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// @param onTrigger: fn to call when the stop triggers
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class TrailingStop extends EventEmitter {
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constructor({trail, initialPrice, onTrigger}) {
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super();
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this.trail = trail;
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this.isLive = true;
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this.onTrigger = onTrigger;
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this.previousPrice = initialPrice;
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this.trailingPoint = initialPrice - this.trail;
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}
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updatePrice(price) {
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if(!this.isLive) {
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return;
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}
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if(price > this.trailingPoint + this.trail) {
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this.trailingPoint = price - this.trail;
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}
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this.previousPrice = price;
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if(price <= this.trailingPoint) {
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this.trigger();
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}
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}
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updateTrail(trail) {
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if(!this.isLive) {
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return;
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}
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this.trail = trail;
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this.trailingPoint = this.previousPrice - this.trail;
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// recheck whether moving the trail triggered.
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this.updatePrice(this.previousPrice);
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}
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trigger() {
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if(!this.isLive) {
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return;
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}
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this.isLive = false;
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if(this.onTrigger) {
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this.onTrigger(this.previousPrice);
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}
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this.emit('trigger', this.previousPrice);
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}
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}
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module.exports = TrailingStop; |