Method parseUpdateExpression

src/parser.ts:1350–1388

()

    // https://tc39.github.io/ecma262/#sec-update-expressions

    parseUpdateExpression(): Node.Expression {
        let expr;
        const startToken = this.lookahead;

        if (this.match('++') || this.match('--')) {
            const node = this.startNode(startToken);
            const token = this.nextToken();
            expr = this.inheritCoverGrammar(this.parseUnaryExpression);
            if (this.context.strict && expr.type === Syntax.Identifier && this.scanner.isRestrictedWord(expr.name)) {
                this.tolerateError(Messages.StrictLHSPrefix);
            }
            if (!this.context.isAssignmentTarget) {
                this.tolerateError(Messages.InvalidLHSInAssignment);
            }
            const prefix = true;
            expr = this.finalize(node, new Node.UpdateExpression(token.value, expr, prefix));
            this.context.isAssignmentTarget = false;
            this.context.isBindingElement = false;
        } else {
            expr = this.inheritCoverGrammar(this.parseLeftHandSideExpressionAllowCall);
            if (!this.hasLineTerminator && this.lookahead.type === Token.Punctuator) {
                if (this.match('++') || this.match('--')) {
                    if (this.context.strict && expr.type === Syntax.Identifier && this.scanner.isRestrictedWord(expr.name)) {
                        this.tolerateError(Messages.StrictLHSPostfix);
                    }
                    if (!this.context.isAssignmentTarget) {
                        this.tolerateError(Messages.InvalidLHSInAssignment);
                    }
                    this.context.isAssignmentTarget = false;
                    this.context.isBindingElement = false;
                    const operator = this.nextToken().value;
                    const prefix = false;
                    expr = this.finalize(this.startNode(startToken), new Node.UpdateExpression(operator, expr, prefix));
                }
            }
        }

        return expr;
    }

    // https://tc39.github.io/ecma262/#sec-unary-operators